Oil is an important _____ material, which can be processed(加工) into many different chemical products, including plastics.
A. primary
B. raw
C. original
D. critical
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Mark _____ his way on to the crowded bus but failed to get a seat.
A. elbowed
B. bowed
C. crowded
D. rowed
This _____ can be used to measure sea surface temperatures.
A. vehicle
B. engine
C. implement
D. instrument
He was so seriously ill that even the most _____ doctors could not cure him.
A. eminent
B. important
C. imminent
D. essential
The _____ is performing a delicate(精细的) operation on Jessica’s knee.
A. dentist
B. surgeon
C. physician
D. nurse
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