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Inference Question
Chào mừng bạn đến với Inference Question
In this lesson, you will learn how to answer Inference questions in the TOEFL Reading section. Inference questions require you to make logical conclusions based on information that is implied but not directly stated in the passage. In other words, they test your ability to understand what the author suggests or implies rather than what is explicitly written. These questions often include words such as imply, suggest, or infer.
To answer them correctly, focus on the relevant part of the passage and use the given facts to reach a reasonable conclusion that must be true based on the information provided.
To answer them correctly, focus on the relevant part of the passage and use the given facts to reach a reasonable conclusion that must be true based on the information provided.
Lesson Introduction
Phần 1
Inference questions ask you to figure out what is true even though it is not directly stated.
Inference questions require you to draw logical conclusions from information that is implied but not directly stated. You must connect ideas and reason out what must be true based on the passage. The correct answer will be supported by the text, but you will need to think one step beyond what is said.
Strategy:
- Read the question carefully. Look for phrases like “What can be inferred…,” “What does the author suggest…,” or “It can be concluded that….” These signal that the answer is implied, not stated directly.
- Locate the relevant part of the passage. Use key words from the question to find the section that contains related information. Do not reread the entire text — focus only on the sentences that connect to the idea in question.
- Identify what the passage says directly. Before guessing, restate the basic facts in your own words. Knowing what is explicitly said helps you understand what is only suggested.
- Think about what must be true, not what could be true. Use logical reasoning to connect the clues. The correct answer is always strongly supported by the passage, even if it isn’t written word-for-word.
- Eliminate wrong choices.
- ❌ Too strong — uses words like “always,” “never,” or “completely.”
- ❌ Unsupported — not based on any part of the passage.
- ❌ Opposite — goes against what the passage implies.
- ❌ Possible but not certain — may seem logical but isn’t directly supported.
Daily Life example (Email):
Subject: Update on Office Renovation Schedule
From: Facilities Department
To: All Staff
Dear Team,
The main lobby renovation is entering its final stage this week. While the work area will remain closed through Friday, access to floors 2–5 is available via the side elevator. Please use the employee entrance near the parking garage between 8:00 a.m. and 6:00 p.m. After that time, security will lock all exterior doors for safety. We appreciate your cooperation as we prepare for reopening early next week.
Best regards,
Facilities Department
What can be inferred from the email?
- The renovation is expected to be completed this Friday.
- Employees can still reach their offices during the renovation using an alternate entrance.
- The building will be closed all week.
- The side elevator will be unavailable until next week.
Detailed Explanation:
The email states that the “main lobby will remain closed through Friday” but that “access to floors 2–5 is available via the side elevator.” This tells us that, even though part of the building is closed, staff can still enter and reach their offices using another route. That is not directly said — it must be inferred.
- (A) is incorrect because the message only says the lobby will remain closed through Friday, not that the entire renovation will be done then.
- (C) is wrong because the email says employees can still access other floors.
- (D) is incorrect because the side elevator is the available route, not closed.
Therefore, the correct answer is (B) because it logically connects the clues — employees still have access, just by a different entrance.
Academic Passage example:
Researchers studying coral bleaching have observed that not all reefs respond equally to rising ocean temperatures. In certain regions, corals exposed to frequent but mild warming events have shown an ability to recover more quickly than those in stable environments. This observation suggests that repeated low-level stress may strengthen the coral’s tolerance to future heatwaves.
Experiments using controlled aquaria revealed that corals pre-exposed to slightly elevated temperatures maintained higher photosynthetic efficiency under subsequent heat stress. These corals were also slower to expel their symbiotic algae, indicating a delay in the onset of bleaching. In contrast, corals kept at constant cool temperatures exhibited a rapid decline in both color and vitality once exposed to the same thermal increase.
Based on these findings, scientists propose that thermal history plays a significant role in determining coral resilience. Reefs experiencing moderate temperature fluctuations may be more adaptable in the short term, though such resilience may come at the cost of long-term metabolic strain. Understanding this balance is key to predicting which coral populations can persist in a warming world.
What can be inferred from the passage?
- Corals in stable environments are better equipped to handle future warming events.
- All coral species respond identically to changes in temperature.
- Prior exposure to mild heat stress can improve coral tolerance to future temperature increases.
- Frequent bleaching permanently damages all coral colonies beyond recovery.
Detailed Explanation:
The passage never says directly that mild heat stress helps corals survive, but it gives several clues: corals exposed to small temperature increases recovered faster and showed stronger resistance during later heat events. These clues logically lead to the conclusion that previous mild stress improves tolerance. This is an inference because it connects information that is suggested, not stated word for word.
- (A) is the opposite of what the passage implies — stable environments make corals less adaptable.
- (B) is wrong because the passage clearly says reefs “do not all respond equally.”
- (D) is too strong — the text never says “permanently” or that all colonies fail.
The correct answer is (C) because it matches the logical conclusion supported by the evidence — that mild heat exposure helps corals build resistance to future stress.
Tips to Remember:
- Inference questions ask you to decide what is implied, not what is stated directly.
- Base your answer only on information in the passage — avoid outside knowledge.
- Look for clues and connections between sentences to find what must be true.
- Reject answers that sound logical but are not clearly supported by the text.
- The best answer is always the one that is strongly implied by the author’s words.
This is the final section of the lesson. I'm ready to start the review exercises!
Review Exercise (1/12)
Complete the multiple choice with paragraph below
Now let's practice.
There were some very unexpected results from the fast development of photography in the 19th century. Due to the use of new equipment and emulsions for photo plate and film coating, images could be created much more quickly. The experiments of photographers Eadweard Muybridge (1830-1904) and Etienne-Jules Marey (1830-1904) show that there are significant differences in the movements of animals and humans, unlike how they had been depicted in previous art forms. Due to a technique called radical cropping – or trimming – of pictures created by the camera, new formats for composition were presented. While some artists rejected the realism of photographs by turning to impressionism and abstraction, certain painters such as Degas copied the accidental effects captured by photography.
We can infer from the paragraph above that one impact that photography had on painting was that it
Nộp bài
done Đúng rồi! Đáp án đúng là "((A))".
clear Chưa chính xác. ((A)) mới là đáp án đúng.
(A) The correct answer is gave artists with new insights into how humans and animals really move. The paragraph says Muybridge’s and Marey’s experiments revealed “significant differences in the movements of animals and humans” compared with how movement had been depicted in earlier art, implying painters gained more accurate information about real motion.
(B) 'indicated that portraying real movement could be as interesting as portrait art' is incorrect because the paragraph does not compare movement painting with portraiture or discuss what was “as interesting” as portraits.
(C) 'enhanced the appeal of painted portraiture among the upper classes' is incorrect because the paragraph discusses motion studies and composition, not social-class demand for portraits.
(D) 'impacted artists on how to improve ways to paint faster' is incorrect because faster image creation refers to photography, not to painters learning to paint more quickly.
(B) 'indicated that portraying real movement could be as interesting as portrait art' is incorrect because the paragraph does not compare movement painting with portraiture or discuss what was “as interesting” as portraits.
(C) 'enhanced the appeal of painted portraiture among the upper classes' is incorrect because the paragraph discusses motion studies and composition, not social-class demand for portraits.
(D) 'impacted artists on how to improve ways to paint faster' is incorrect because faster image creation refers to photography, not to painters learning to paint more quickly.
Thi lại
Complete the multiple choice with paragraph below
Now let's practice.
Scientists have discovered huge amounts of sand and drift material deposits on the ridges that form Cape Cod and Long Island, along the east coast of the United States. The regions covered by this material were so large that it was believed that the ice which deposited it came from a glacier bigger than Antarctic or Greenland. Scientists, such as Agassiz, persuaded the general population and other geologists that glaciation had occurred, from the North and South Poles, stretching into areas that now experience moderate temperatures. It was at this time that the ice age was discussed. Thanks to radiocarbon dating of logs buried in the drift material, we are now aware that glaciation occurred during the Pleistocene era. This period took place from 1.8 million to 10,000 years ago, and the drift material was not harsh but soft, like sediment.
We can infer from the paragraph above that Agassiz and other scientists of this time were not able to determine
Nộp bài
done Đúng rồi! Đáp án đúng là "((B))".
clear Chưa chính xác. ((B)) mới là đáp án đúng.
(B) The correct answer is the exact dates at which drifts had been deposited during the last ice age. The paragraph indicates Agassiz and others argued for glaciation based on the size of deposits, but it says “Thanks to radiocarbon dating… we are now aware” of the Pleistocene timing, implying scientists at that time did not have the dating method to determine exact dates.
(A) 'which geographic regions had been covered with ice sheets in the last ice age' is incorrect because the paragraph says deposits were found on Cape Cod and Long Island and that scientists believed glaciation extended into areas with moderate temperatures, indicating they could infer coverage regions.
(C) 'the exact composition of the drifts laid during the last ice age' is incorrect because the paragraph describes the drift material as “not harsh but soft, like sediment,” indicating composition/texture was observed.
(D) 'how far south along the east coast of the United States the ice had advanced during the last ice age' is incorrect because the paragraph specifies deposits along the east coast (Cape Cod and Long Island) and discusses the extent of glaciation, suggesting they could estimate how far it reached geographically, even if not its exact dates.
(A) 'which geographic regions had been covered with ice sheets in the last ice age' is incorrect because the paragraph says deposits were found on Cape Cod and Long Island and that scientists believed glaciation extended into areas with moderate temperatures, indicating they could infer coverage regions.
(C) 'the exact composition of the drifts laid during the last ice age' is incorrect because the paragraph describes the drift material as “not harsh but soft, like sediment,” indicating composition/texture was observed.
(D) 'how far south along the east coast of the United States the ice had advanced during the last ice age' is incorrect because the paragraph specifies deposits along the east coast (Cape Cod and Long Island) and discusses the extent of glaciation, suggesting they could estimate how far it reached geographically, even if not its exact dates.
Thi lại
Complete the multiple choice with paragraph below
Now let's practice.
In Chihuahua, Mexico, a bright and huge meteor entered the atmosphere of the Earth, disintegrated into several pieces, and fell to the ground. Its pieces were spread over the land below. This incident occurred on the 8th of February, 1969. The region affected was 10 miles in width and 50 miles in length. A village in Mexico called Pueblito de Allende is where the first part of this meteorite was found. The two tons of meteorite fragments found are called Allende after the village.
What can be inferred regarding the huge meteor that arrived in the atmosphere of the earth on the 8th of February, 1969?
Nộp bài
done Đúng rồi! Đáp án đúng là "((A))".
clear Chưa chính xác. ((A)) mới là đáp án đúng.
(A) The correct answer is It was heavier than two tons. The paragraph states that “two tons of meteorite fragments” were found, which implies that the meteor originally had to be more than two tons before breaking apart, since some material could have been lost or not recovered.
(B) 'It was more than ten miles wide' is incorrect because “10 miles in width and 50 miles in length” describes the area over which fragments were scattered, not the meteor’s physical size.
(C) 'This meteor was the largest one to hit Mexico in history' is incorrect because the paragraph gives no comparison to other meteors in Mexican history.
(D) 'It smashed into more fragments than any other meteor' is incorrect because the paragraph says it broke into several pieces but provides no basis for comparing the number of fragments to other events.
(B) 'It was more than ten miles wide' is incorrect because “10 miles in width and 50 miles in length” describes the area over which fragments were scattered, not the meteor’s physical size.
(C) 'This meteor was the largest one to hit Mexico in history' is incorrect because the paragraph gives no comparison to other meteors in Mexican history.
(D) 'It smashed into more fragments than any other meteor' is incorrect because the paragraph says it broke into several pieces but provides no basis for comparing the number of fragments to other events.
Thi lại
Complete the multiple choice with paragraph below
Now let's practice.
In the fourteenth century, a number of political developments cut Europe's overland trade routes to southern and eastern Asia, with which Europe had had important and highly profitable commercial ties since the twelfth century. This development, coming as it did when the bottom had fallen out of the European economy, provided an impetus to a long-held desire to secure direct relations with the East by establishing a sea trade. Widely reported, if somewhat distrusted, accounts by figures like the famous traveler from Venice, Marco Polo, of the willingness of people in China to trade with Europeans and of the immensity of the wealth to be gained by such contact made the idea irresistible. Possibilities for trade seemed promising, but no hope existed for maintaining the traditional routes over land A new way had to be found.
The chief problem was technological: How were the Europeans to reach the East? Europe's maritime tradition had developed in the context of easily navigable seas—the Mediterranean, the Baltic, and. to a lesser extent, the North Sea between England and the Continent—not of vast oceans. New types of ships were needed, new methods of finding one's way, new techniques for financing so vast a scheme. The sheer scale of the investment it took to begin commercial expansion at sea reflects the immensity of the profits that such East-West trade could create. Spices were the most sought-after commodities. Spices not only dramatically improved the taste of the European diet but also were used to manufacture perfumes and certain medicines. But even high-priced commodities like spices had to be transported in large bulk in order to justify the expense and trouble of sailing around the African continent all the way to India and China.
The chief problem was technological: How were the Europeans to reach the East? Europe's maritime tradition had developed in the context of easily navigable seas—the Mediterranean, the Baltic, and. to a lesser extent, the North Sea between England and the Continent—not of vast oceans. New types of ships were needed, new methods of finding one's way, new techniques for financing so vast a scheme. The sheer scale of the investment it took to begin commercial expansion at sea reflects the immensity of the profits that such East-West trade could create. Spices were the most sought-after commodities. Spices not only dramatically improved the taste of the European diet but also were used to manufacture perfumes and certain medicines. But even high-priced commodities like spices had to be transported in large bulk in order to justify the expense and trouble of sailing around the African continent all the way to India and China.
It can be inferred from paragraph 2 that spices from Asia were desirable in Europe in the Middle Ages because they
Nộp bài
done Đúng rồi! Đáp án đúng là "((B))".
clear Chưa chính xác. ((B)) mới là đáp án đúng.
(B) The correct answer is could not be produced in European countries. Paragraph 2 explains that Europeans were willing to make an expensive, difficult voyage to obtain spices because the profits were immense and the commodities were highly sought-after, implying spices were not readily available from European production.
(A) 'were easily transported in large quantities' is incorrect because the paragraph implies the opposite: even high-priced commodities had to be shipped “in large bulk” to justify the voyage, which suggests transport was challenging and costly.
(C) 'could be traded for products such as perfumes and medicines' is incorrect because the paragraph says spices were used to manufacture perfumes and medicines, not that they were traded for them.
(D) 'were expected to increase in value over time' is incorrect because the paragraph discusses immediate demand and profit, not long-term appreciation in value.
(A) 'were easily transported in large quantities' is incorrect because the paragraph implies the opposite: even high-priced commodities had to be shipped “in large bulk” to justify the voyage, which suggests transport was challenging and costly.
(C) 'could be traded for products such as perfumes and medicines' is incorrect because the paragraph says spices were used to manufacture perfumes and medicines, not that they were traded for them.
(D) 'were expected to increase in value over time' is incorrect because the paragraph discusses immediate demand and profit, not long-term appreciation in value.
Thi lại
Complete the multiple choice with paragraph below
Now let's practice.
By the eighteenth century, Britain was experiencing a severe shortage of energy. Because of the growth of population, most of the great forests of medieval Britain had long ago been replaced by fields of grain and hay. Wood was in ever-shorter supply, yet it remained tremendously important. It served as the primary source of heat for all homes and industries and as a basic raw material. Processed wood (charcoal) was the fuel that was mixed with iron ore in the blast furnace to produce pig iron (raw iron). The iron industry’s appetite for wood was enormous, and by 1740 the British iron industry was stagnating. Vast forests enabled Russia to become the world’s leading producer of iron, much of which was exported to Britain. But Russia’s potential for growth was limited too, and in a few decades Russia would reach the barrier of inadequate energy that was already holding England back.
What can be inferred from paragraph 1 about Britain's short supply of wood in the eighteenth century?
Nộp bài
done Đúng rồi! Đáp án đúng là "((B))".
clear Chưa chính xác. ((B)) mới là đáp án đúng.
(B) The correct answer is A growing population had required cutting down forests to increase available land for farming. The paragraph says that because of population growth, “most of the great forests… had long ago been replaced by fields of grain and hay,” implying forests were cleared to create farmland.
(A) 'Wood from Britain’s great forests was being exported to other countries for profit' is incorrect because the paragraph emphasizes wood scarcity within Britain, not export.
(C) 'Larger families required the construction of larger homes made from wood' is incorrect because the paragraph links wood shortage to forests being replaced by farmland and heavy industrial use, not to bigger wooden homes.
(D) 'What was left of the great forests after the medieval period was being strictly protected' is incorrect because the paragraph does not mention protection policies; it describes depletion and shortage.
(A) 'Wood from Britain’s great forests was being exported to other countries for profit' is incorrect because the paragraph emphasizes wood scarcity within Britain, not export.
(C) 'Larger families required the construction of larger homes made from wood' is incorrect because the paragraph links wood shortage to forests being replaced by farmland and heavy industrial use, not to bigger wooden homes.
(D) 'What was left of the great forests after the medieval period was being strictly protected' is incorrect because the paragraph does not mention protection policies; it describes depletion and shortage.
Thi lại
Complete the multiple choice with paragraph below
Now let's practice.
Geothermal energy becomes available in a practical form when underground heat is transferred by water that is heated as it passes through a subsurface region of hot rocks (a heat reservoir) that may be hundreds or thousands of feet deep. The water is usually naturally occurring groundwater that seeps down along fractures in the rock; less typically, the water is artificially introduced by being pumped down from the surface. The water is brought to the surface, as a liquid or steam, through holes drilled for the purpose. By far the most abundant form of geothermal energy occurs at the relatively low temperatures of 80°to 180°centigrade. Water circulated through heat reservoirs in this temperature range is able to extract enough heat to warm residential, commercial, and industrial spaces. More than 20,000 apartments in France are now heated by warm underground water drawn from a heat reservoir in a geologic structure near Paris called the Paris Basin. Iceland sits on a volcanic structure known as the Mid-Atlantic Ridge. Reykjavik, the capital of Iceland, is entirely heated by geothermal energy derived from volcanic heat.
Geothermal reservoirs with temperatures above 180°centigrade are useful for generating electricity. They occur primarily in regions of recent volcanic activity as hot, dry rock; natural hot water; or natural steam. The latter two sources are limited to those few areas where surface water seeps down through underground faults or fractures to reach deep rocks heated by the recent activity of molten rock material. The world's largest supply of natural steam occurs at The Geysers, 120 kilometers north of San Francisco, California. In the 1990s enough electricity to meet about half the needs of San Francisco was being generated there. This facility was then in its third decade of production and was beginning to show signs of decline, perhaps because of over development. By the late 1990s some 70 geothermal electric-generating plants were in operation in California, Utah, Nevada, and Hawaii, generating enough power to supply about a million people. Eighteen countries now generate electricity using geothermal heat.
Geothermal reservoirs with temperatures above 180°centigrade are useful for generating electricity. They occur primarily in regions of recent volcanic activity as hot, dry rock; natural hot water; or natural steam. The latter two sources are limited to those few areas where surface water seeps down through underground faults or fractures to reach deep rocks heated by the recent activity of molten rock material. The world's largest supply of natural steam occurs at The Geysers, 120 kilometers north of San Francisco, California. In the 1990s enough electricity to meet about half the needs of San Francisco was being generated there. This facility was then in its third decade of production and was beginning to show signs of decline, perhaps because of over development. By the late 1990s some 70 geothermal electric-generating plants were in operation in California, Utah, Nevada, and Hawaii, generating enough power to supply about a million people. Eighteen countries now generate electricity using geothermal heat.
Which of the following can be inferred from paragraphs 1 and 2 about geothermal reservoirs?
Nộp bài
done Đúng rồi! Đáp án đúng là "((D))".
clear Chưa chính xác. ((D)) mới là đáp án đúng.
(D) The correct answer is A higher geothermal reservoir temperature is needed to generate electricity than is needed to heat homes. Paragraph 1 says the most abundant reservoirs (80°–180°C) can heat buildings, while paragraph 2 states reservoirs “above 180°C” are useful for generating electricity, showing electricity requires higher temperatures.
(A) 'Volcanic heat is associated only with geothermal reservoirs that have a temperature over 180°centigrade' is incorrect because paragraph 1 gives Iceland’s heating as geothermal energy derived from volcanic heat, showing volcanic heat can be used for lower-temperature heating too.
(B) 'More countries produce power from geothermal reservoirs than use them for heating buildings' is incorrect because the passage gives examples of heating in France and Iceland and notes 18 countries generate electricity, but it does not compare which number is larger.
(C) 'Most geothermal reservoirs are suitable for producing electricity' is incorrect because the passage says the most abundant geothermal energy is at relatively low temperatures (80°–180°C), which is primarily for heating, not electricity.
(A) 'Volcanic heat is associated only with geothermal reservoirs that have a temperature over 180°centigrade' is incorrect because paragraph 1 gives Iceland’s heating as geothermal energy derived from volcanic heat, showing volcanic heat can be used for lower-temperature heating too.
(B) 'More countries produce power from geothermal reservoirs than use them for heating buildings' is incorrect because the passage gives examples of heating in France and Iceland and notes 18 countries generate electricity, but it does not compare which number is larger.
(C) 'Most geothermal reservoirs are suitable for producing electricity' is incorrect because the passage says the most abundant geothermal energy is at relatively low temperatures (80°–180°C), which is primarily for heating, not electricity.
Thi lại
Complete the multiple choice with paragraph below
Now let's practice.
[1] In 1769 in a little town in Oxfordshire, England, a child with the very ordinary name of William Smith was born into the poor family of a village blacksmith. He received rudimentary village schooling, but mostly he roamed his uncle's farm collecting the fossils that were so abundant in the rocks of the Cotswold hills. When he grew older, William Smith taught himself surveying from books he bought with his small savings, and at the age of eighteen he was apprenticed to a surveyor of the local parish. He then proceeded to teach himself geology, and when he was twenty-four, he went to work for the company that was excavating the Somerset Coal Canal in the south of England.
[2] This was before the steam locomotive, and canal building was at its height. The companies building the canals to transport coal needed surveyors to help them find the coal deposits worth mining as well as to determine the best courses for the canals. This job gave Smith an opportunity to study the fresh rock outcrops created by the newly dug canal. He later worked on similar jobs across the length and breadth of England, all the while studying the newly revealed strata and collecting all the fossils he could find. Smith used mail coaches to travel as much as 10,000 miles per year. In 1815 he published the first modern geological map, “A Map of the Strata of England and Wales with a Part of Scotland,”a map so meticulously researched that it can still be used today.
[2] This was before the steam locomotive, and canal building was at its height. The companies building the canals to transport coal needed surveyors to help them find the coal deposits worth mining as well as to determine the best courses for the canals. This job gave Smith an opportunity to study the fresh rock outcrops created by the newly dug canal. He later worked on similar jobs across the length and breadth of England, all the while studying the newly revealed strata and collecting all the fossils he could find. Smith used mail coaches to travel as much as 10,000 miles per year. In 1815 he published the first modern geological map, “A Map of the Strata of England and Wales with a Part of Scotland,”a map so meticulously researched that it can still be used today.
Which of the following can be inferred from paragraph 2 about canal building?
Nộp bài
done Đúng rồi! Đáp án đúng là "((B))".
clear Chưa chính xác. ((B)) mới là đáp án đúng.
(B) The correct answer is Canal building decreased after the steam locomotive was invented. Paragraph 2 states, “This was before the steam locomotive, and canal building was at its height,” which implies that once steam locomotives arrived, canal building was no longer at its peak and likely declined.
(A) 'Canals were built primarily in the south of England rather than in other regions' is incorrect because the paragraph says Smith later worked across the “length and breadth of England,” implying canal projects were widespread.
(C) 'Canal building made it difficult to study rock strata which often became damaged in the process' is incorrect because the paragraph says the job gave Smith “an opportunity to study the fresh rock outcrops” created by digging, indicating it helped rather than harmed study.
(D) 'Canal builders hired surveyors like Smith to examine exposed rock strata' is incorrect because the paragraph says companies needed surveyors to find coal deposits and determine canal routes, not to study strata for scientific purposes.
(A) 'Canals were built primarily in the south of England rather than in other regions' is incorrect because the paragraph says Smith later worked across the “length and breadth of England,” implying canal projects were widespread.
(C) 'Canal building made it difficult to study rock strata which often became damaged in the process' is incorrect because the paragraph says the job gave Smith “an opportunity to study the fresh rock outcrops” created by digging, indicating it helped rather than harmed study.
(D) 'Canal builders hired surveyors like Smith to examine exposed rock strata' is incorrect because the paragraph says companies needed surveyors to find coal deposits and determine canal routes, not to study strata for scientific purposes.
Thi lại
Complete the multiple choice with paragraph below
Now let's practice.
[1] Many signals that animals make seem to impose on the signalers costs that are overly damaging. A classic example is noisy begging by nestling songbirds when a parent returns to the nest with food. These loud cheeps and peeps might give the location of the nest away to a listening hawk or raccoon, resulting in the death of the defenseless nestlings.
[2] Further evidence for the costs of begging comes from a study of differences in the begging calls of warbler species that nest on the ground versus those that nest in the relative safety of trees. The young of ground-nesting warblers produce begging cheeps of higher frequencies than do their tree-nesting relatives. These higher-frequency sounds do not travel as far, and so may better conceal the individuals producing them, who are especially vulnerable to predators in their ground nests. The hypothesis that begging calls have evolved properties that reduce their potential for attracting predators yields a prediction: baby birds of species that experience high rates of nest predation should produce softer begging signals of higher frequency than nestlings of other species less often victimized by nest predators. This prediction was supported by data collected in one survey of 24 species from an Arizona forest, more evidence that predator pressure favors the evolution of begging calls that are hard to detect and pinpoint.
[3] Given that predators can make it costly to beg for food, what benefit do begging nestlings derive from their communications? One possibility is that a noisy baby bird provides accurate signals of its real hunger and good health, making it worthwhile for the listening parent to give it food in a nest where several other offspring are usually available to be fed. If this hypothesis is true, then it follows that nestlings should adjust the intensity of their signals in relation to the signals produced by their nestmates, who are competing for parental attention. When experimentally deprived baby robins are placed in a nest with normally fed siblings, the hungry nestlings beg more loudly than usual—but so do their better-fed siblings, though not as loudly as the hungrier birds.
[4] If parent birds use begging intensity to direct food to healthy offspring capable of vigorous begging, then parents should make food delivery decisions on the basis of their offsprings’ calls. Indeed, if you take baby tree swallows out of a nest for an hour feeding half the set and starving the other half, when the birds are replaced in the nest, the starved youngsters beg more loudly than the fed birds, and the parent birds feed the active beggars more than those who beg less vigorously.
[2] Further evidence for the costs of begging comes from a study of differences in the begging calls of warbler species that nest on the ground versus those that nest in the relative safety of trees. The young of ground-nesting warblers produce begging cheeps of higher frequencies than do their tree-nesting relatives. These higher-frequency sounds do not travel as far, and so may better conceal the individuals producing them, who are especially vulnerable to predators in their ground nests. The hypothesis that begging calls have evolved properties that reduce their potential for attracting predators yields a prediction: baby birds of species that experience high rates of nest predation should produce softer begging signals of higher frequency than nestlings of other species less often victimized by nest predators. This prediction was supported by data collected in one survey of 24 species from an Arizona forest, more evidence that predator pressure favors the evolution of begging calls that are hard to detect and pinpoint.
[3] Given that predators can make it costly to beg for food, what benefit do begging nestlings derive from their communications? One possibility is that a noisy baby bird provides accurate signals of its real hunger and good health, making it worthwhile for the listening parent to give it food in a nest where several other offspring are usually available to be fed. If this hypothesis is true, then it follows that nestlings should adjust the intensity of their signals in relation to the signals produced by their nestmates, who are competing for parental attention. When experimentally deprived baby robins are placed in a nest with normally fed siblings, the hungry nestlings beg more loudly than usual—but so do their better-fed siblings, though not as loudly as the hungrier birds.
[4] If parent birds use begging intensity to direct food to healthy offspring capable of vigorous begging, then parents should make food delivery decisions on the basis of their offsprings’ calls. Indeed, if you take baby tree swallows out of a nest for an hour feeding half the set and starving the other half, when the birds are replaced in the nest, the starved youngsters beg more loudly than the fed birds, and the parent birds feed the active beggars more than those who beg less vigorously.
It can be inferred from paragraphs 3 and 4 that parent songbirds normally do not feed
Nộp bài
done Đúng rồi! Đáp án đúng là "((A))".
clear Chưa chính xác. ((A)) mới là đáp án đúng.
(A) The correct answer is nestlings that are too weak to beg for food as vigorously as their nestmates. Paragraphs 3 and 4 suggest parents use begging intensity to decide where to deliver food, and experiments show parents feed louder, more active beggars more than those who beg less vigorously, implying weak, low-intensity beggars are less likely to be fed.
(B) 'more than one hungry nestling during a single visit to the nest' is incorrect because the passage does not limit feeding to only one nestling per visit; it focuses on which nestlings get more food.
(C) 'offspring that were fed by the parents on the previous visit to the nest' is incorrect because the passage does not say parents track previous feeding; it says they respond to current begging intensity.
(D) 'nestlings that have been removed and then later put back into their nest' is incorrect because removal is part of an experiment, and the parents still feed the louder beggars after the chicks are returned.
(B) 'more than one hungry nestling during a single visit to the nest' is incorrect because the passage does not limit feeding to only one nestling per visit; it focuses on which nestlings get more food.
(C) 'offspring that were fed by the parents on the previous visit to the nest' is incorrect because the passage does not say parents track previous feeding; it says they respond to current begging intensity.
(D) 'nestlings that have been removed and then later put back into their nest' is incorrect because removal is part of an experiment, and the parents still feed the louder beggars after the chicks are returned.
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Complete the multiple choice with paragraph below
Now let's practice.
Many plants - one or more species of at least 68 different families - can secrete nectar even when they have no blossoms, because they bear extrafloral nectaries (structures that produce nectar) on stems, leaves, leaf stems, or other structures. These plants usually occur where ants are abundant, most in the tropics but some in temperate areas. Among those of northeastern North America are various plums, cherries, roses, hawthorns, poplars, and oaks. Like floral nectar, extrafloral nectar consists mainly of water with a high content of dissolved sugars and, in some plants, small amounts of amino acids. The extrafloral nectaries of some plants are known to attract ants and other insects, but the evolutionary history of most plants with these nectaries is unknown. Nevertheless, most ecologists believe that all extrafloral nectaries attract insects that will defend the plant.
Ants are probably the most frequent and certainly the most persistent defenders of plants. Since the highly active worker ants require a great deal of energy, plants exploit this need by providing extrafloral nectar that supplies ants with abundant energy. To return this favor, ants guard the nectaries, driving away or killing intruding insects that might compete with ants for nectar. Many of these intruders are herbivorous and would eat the leaves of the plants.
Ants are probably the most frequent and certainly the most persistent defenders of plants. Since the highly active worker ants require a great deal of energy, plants exploit this need by providing extrafloral nectar that supplies ants with abundant energy. To return this favor, ants guard the nectaries, driving away or killing intruding insects that might compete with ants for nectar. Many of these intruders are herbivorous and would eat the leaves of the plants.
What can be inferred from paragraph 2 about the ants that are attracted to the extrafloral nectaries?
Nộp bài
done Đúng rồi! Đáp án đúng là "((A))".
clear Chưa chính xác. ((A)) mới là đáp án đúng.
(A) The correct answer is They do not eat the leaves of the plants that produce extrafloral nectar. Paragraph 2 says ants drive away or kill “intruding insects” that might compete for nectar and notes many intruders are herbivorous and would eat the leaves, implying the ants themselves are defenders rather than leaf-eaters.
(B) 'They live almost entirely on extrafloral nectar' is incorrect because the paragraph says nectar supplies abundant energy, but it does not claim it is their only or almost-only food source.
(C) 'They spend most of their energy guarding extrafloral nectaries' is incorrect because the paragraph emphasizes worker ants require a great deal of energy and plants supply it; it does not say most of that energy is spent guarding.
(D) 'They frequently fight among themselves over extrafloral nectar' is incorrect because the paragraph discusses ants fighting intruders, not each other.
(B) 'They live almost entirely on extrafloral nectar' is incorrect because the paragraph says nectar supplies abundant energy, but it does not claim it is their only or almost-only food source.
(C) 'They spend most of their energy guarding extrafloral nectaries' is incorrect because the paragraph emphasizes worker ants require a great deal of energy and plants supply it; it does not say most of that energy is spent guarding.
(D) 'They frequently fight among themselves over extrafloral nectar' is incorrect because the paragraph discusses ants fighting intruders, not each other.
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Complete the multiple choice with paragraph below
Now let's practice.
It should be obvious that cetaceans—whales, porpoises, and dolphins—are mammals. They breathe through lungs, not through gills, and give birth to live young. Their streamlined bodies, the absence of hind legs, and the presence of a fluke and blowhole cannot disguise their affinities with land dwelling mammals. However, unlike the cases of sea otters and pinnipeds (seals, sea lions, and walruses, whose limbs are functional both on land and at sea), it is not easy to envision what the first whales looked like. Extinct but already fully marine cetaceans are known from the fossil record. How was the gap between a walking mammal and a swimming whale bridged? Missing until recently were fossils clearly intermediate, or transitional, between land mammals and cetaceans.
Which of the following can be inferred from paragraph 1 about early sea otters?
Nộp bài
done Đúng rồi! Đáp án đúng là "((A))".
clear Chưa chính xác. ((A)) mới là đáp án đúng.
(A) The correct answer is It is not difficult to imagine what they looked like. The paragraph says that unlike early whales, sea otters and pinnipeds have limbs functional on land and sea, so it is easier to envision their form and the transition, implying early sea otters are easier to picture.
(B) 'There were great numbers of them' is incorrect because the paragraph provides no information about population size.
(C) 'They lived in the sea only' is incorrect because the paragraph describes sea otters as having limbs functional both on land and at sea, implying they are not exclusively marine.
(D) 'They did not leave many fossil remains' is incorrect because the paragraph does not discuss sea otter fossils; it discusses the lack of transitional whale fossils until recently.
(B) 'There were great numbers of them' is incorrect because the paragraph provides no information about population size.
(C) 'They lived in the sea only' is incorrect because the paragraph describes sea otters as having limbs functional both on land and at sea, implying they are not exclusively marine.
(D) 'They did not leave many fossil remains' is incorrect because the paragraph does not discuss sea otter fossils; it discusses the lack of transitional whale fossils until recently.
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Complete the multiple choice with paragraph below
Now let's practice.
When it comes to physiology, the leatherback turtle is, in some ways, more like a reptilian whale than a turtle. It swims farther into the cold of the northern and southern oceans than any other sea turtle, and it deals with the chilly waters in a way unique among reptiles.
What can be inferred about whales from paragraph 1?
Nộp bài
done Đúng rồi! Đáp án đúng là "((B))".
clear Chưa chính xác. ((B)) mới là đáp án đúng.
(B) The correct answer is Their bodies are built in a way that helps them manage extremely cold temperatures. The sentence compares the leatherback turtle to a “reptilian whale” specifically in how it handles chilly waters, implying whales are well adapted to cold-water conditions.
(A) 'They are considered by some to be reptiles' is incorrect because whales are mentioned only as a comparison; nothing suggests whales are reptiles.
(C) 'They are distantly related to leatherback turtles' is incorrect because the comparison is about physiology, not evolutionary relatedness.
(D) 'They can swim farther than leatherback turtles' is incorrect because the paragraph says leatherbacks swim farther into cold northern and southern oceans than any other sea turtle; it does not compare whale swimming range to leatherbacks.
(A) 'They are considered by some to be reptiles' is incorrect because whales are mentioned only as a comparison; nothing suggests whales are reptiles.
(C) 'They are distantly related to leatherback turtles' is incorrect because the comparison is about physiology, not evolutionary relatedness.
(D) 'They can swim farther than leatherback turtles' is incorrect because the paragraph says leatherbacks swim farther into cold northern and southern oceans than any other sea turtle; it does not compare whale swimming range to leatherbacks.
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Complete the multiple choice with paragraph below
Now let's practice.
We all know that many more people today are right-handed than left-handed. Can one trace this same pattern far back in prehistory? Much of the evidence about right-hand versus left-hand dominance comes from stencils and prints found in rock shelters in Australia and elsewhere, and in many Ice Age caves in France, Spain, and Tasmania. When a left hand has been stenciled, this implies that the artist was right-handed, and vice versa. Even though the paint was often sprayed on by mouth, one can assume that the dominant hand assisted in the operation. One also has to make the assumption that hands were stenciled palm downward—a left hand stenciled palm upward might of course look as if it were a right hand. Of 158 stencils in the French cave of Gargas, 136 have been identified as left, and only 22 as right; right-handedness was therefore heavily predominant.
It can be inferred from paragraph 1 that even when paint was sprayed by mouth to make a hand stencil
Nộp bài
done Đúng rồi! Đáp án đúng là "((B))".
clear Chưa chính xác. ((B)) mới là đáp án đúng.
(B) The correct answer is the stenciled hand was the weaker hand. The paragraph explains that a left-hand stencil implies the artist was right-handed (the dominant hand likely helped operate the spraying), suggesting the stenciled hand itself was typically the non-dominant hand.
(A) 'there was no way to tell which hand was stenciled' is incorrect because the paragraph describes how researchers identify left vs. right stencils and use them to infer handedness.
(C) 'the stenciled hand was the dominant hand' is incorrect because the paragraph states the dominant hand likely assisted with making the stencil, which implies the other hand was the one being stenciled.
(D) 'artists stenciled more images of the dominant hand than they did of the weak' is incorrect because the evidence given (many left-hand stencils) suggests the opposite pattern would occur if most artists were right-handed.
(A) 'there was no way to tell which hand was stenciled' is incorrect because the paragraph describes how researchers identify left vs. right stencils and use them to infer handedness.
(C) 'the stenciled hand was the dominant hand' is incorrect because the paragraph states the dominant hand likely assisted with making the stencil, which implies the other hand was the one being stenciled.
(D) 'artists stenciled more images of the dominant hand than they did of the weak' is incorrect because the evidence given (many left-hand stencils) suggests the opposite pattern would occur if most artists were right-handed.
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