Question

【题目】Many birds are often heard ____ happily in the park.

A.singB.singingC.sangD.to sing

Answer 1

【答案】D

【解析】

句意：许多鸟经常被听到在公园里高兴地唱歌。

A. sing唱；原形；B. singing唱，现在分词；C. sang唱，过去式；D. to sing唱。动词不定式。短语hear sb. do sth.表示听见某人做某事，被动语态是sb. be heard to do sth.表示某人被听到去做某事。根据题意，故选D。