My set of keys old but your keys are new.A. amB. isC. areD. be

问题补充：

My set of keys old, but your keys are new.

A. am

B. is

C. are

D. be

答案：

A. am

B. is

(答案→)C. are

D. be

解析：本题的主语是复数，故be用are，故本题选C。