I hear him sing the English song.改成被动句Emmashao个个对的，但为什么是这样？
网友回答
He is heard to sing the English song.
因为在主动语态中,感官动词hear要省to,但在被动语态中,感官动词hear不能省to.
======以下答案可供参考======
供参考答案1:
He is heard sing the English song by me.
供参考答案2:
He is heard singing the English song.
供参考答案3:
The English song he sang was heard by me
供参考答案4:
He is heard sung the English song
供参考答案5:
He is heard to sing the English song by me.