问题 选择题

—I knocked but nobody answered the door.

----They _____asleep then and didn’t hear you.

A.must be

B.should be

C.must have been

D.should have been

答案

答案:C

考察虚拟语气.句意:我敲门但是没有人开门._那时候他们一定是已经睡着了,没有听到你敲门. “must+have+done”表示对过去事情的肯定推测,译成“一定做过某事”故选C.

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