this set of keys yours?A. AreB. isC. amD. Is

问题补充：

this set of keys yours?

A. Are

B. is

C. am

D. Is

答案：

A. Are

B. is

C. am

(答案→)D. Is

解析：通过this set of keys “这串钥匙”可知，是一串，而不是多串，所以这里的主语应该是单数，所以应该用is ；又因为放在开头，所以本题选D.