6.I______theclassroomwhenhe____asong.

更新时间2020-11-12 22:52:03

A. went past; heard to sing      B. passed; was heard singing C. went by;heard singing D.was passing by;was heard to sing
请问选什么并解答一下 谢谢

答案D

A. went past; heard to sing      第二个答案不对。他听到（？）唱歌，没有宾语。

B. passed; was heard singing  我经过教室时，听到他在唱歌。（pass少了个by）

C. went by; heard singing   第二个答案不对。他听到（？）正在唱歌，没有宾语。

D.was passing by; was heard to sing 我正在经过教室，突然听到他唱歌。

when这里的意思是：and at that time