The girl was often heard happily in her room.A. singB. to singC. singingD. sings

发布时间：2020-08-21 14:14:20

The girl was often heard      happily in her room.
A. sing
B. to sing
C. singing
D. sings

网友回答

A. sing
(答案→)B. to sing
C. singing
D. sings
解析：hear sb do sth表示听到某人做某事，变为被动语态时其句式结构为 be heard to do sth.
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