–Are these your rulers? – Yes .A. these areB. it isC. they areD. they aren’t

问题补充：

–Are these your rulers? – Yes, .

A. these are

B. it is

C. they are

D. they aren’t

答案：

A. these are

B. it is

(答案→)C. they are

D. they aren’t

解析：句意：--这些是你的尺子吗？--是的。当上句的主语是these时，下文在回答的时候不能用these，而用they，因为上句是are所以下文也用are。故选C。