She was often heard ( ) in English.AsingBsingingCsungDto sing答案选D,为什么不选A,

题目

She was often heard ( ) in English.AsingBsingingCsungDto sing答案选D,为什么不选A,

答案

在主动句里,hear的用法是hear sb.do sth.听见某人做某事
但在其被动形式要加上to,变为be heard to do sth.被听见做某事
感官动词的词组变成被动语态时,要变成be ...to do sth.,必须要加上不定式符号to