magnet

definition: 
A piece of iron (or an ore, alloy, or other material)
sentence: 
Understanding more complex substances is the key to designing materials for stronger magnets in order to build more efficient and powerful electrical generators and motors.
Iron, cobalt and nickel are the best known metallic magnets, and their magnetic properties are governed by the conduction electrons that are free to move throughout the metal.
difficulty: 
easy
toefl frequency: 
2
toefl classification: 
adverb: 
adjective: 
adverb sentence: 
adjective sentence: 
verb: 
verb sentence: