问题
选择题
The girl was often heard ______ happily in her room.
A．sing
B．to sing
C．singing
D．sings
答案
答案：B
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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The girl was often heard ______ happily in her room.
A．sing
B．to sing
C．singing
D．sings
答案：B
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.