Submitted by admin on Mon, 04/14/2014 - 23:07
definition:
A grey crystalline allotropic form of carbon which occurs as a mineral in some rocks and can be made from coke. It is used as a solid lubricant, in pencils, and as a moderator in nuclear reactors
sentence:
One possibility of this sort of manipulation could turn carbon into either graphite or diamond.
difficulty:
hard
toefl frequency:
1
toefl classification: