The department purchased______ to improve the working conditions there.
A. a new equipment
B. a new piece of equipment
C. new equipments
D. new pieces of equipments
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In the United States, presidential elections are held once ______.
A. every four year
B. every four years
C. four every year
D. four every years
At least we are required to write five______ everyear.
A. theses
B. thesis
C. thesises
D. pieces of thesis
A hammer_______ a means of driving a nail.
A. was
B. is
C. are
D. were
He has given a series of ________ of his loyalty and sincerity.
A. proof
B. prooves
C. proofs
D. proofes
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