“I know she was in because I heard her radio but she didn’t open the door.” “Shethe bell.

问题补充：

“I know she was in because I heard her radio, but she didn’t open the door.” “Shethe bell.”

A. may not be hearing

B. may not have heard

C. must not have heard

D. must not be hearing

答案：

A. may not be hearing

(答案→)B. may not have heard

C. must not have heard

D. must not be hearing

解析：考查情态动词。根据语境可知为对过去事情的推测，故用情态动词+ have done。may have done过去也许做过某事。根据句意为：她也许没有听到铃声。故选B。