就拿h背判直袁垂ear sb do sth举例就把sba提前,hear变为令青钟你龙审华heard,但是来自要注意do原来是不带to的不定式做宾语补足语的,但是在被动语态中要将to还原,加到to前,即do变为to doeg;i heard him sing yesterday被;he was heard to sing yesterday