在用于被动结构时,主动结构中的间接宾语变为主语时,直接宾语仍然保留在谓语后面；直接宾语变为主语时,间接宾语前通常加上介词for/to
有些动词后跟不带to的不定式作宾语补足语,但改为被动结构后要加上“to”.例如
We heard him sing in his room just now.
---He was heard to sing in his room just now.
不带to的不定式作宾语补足语变为被动语态时,不定式前必须补加上不定式符号to
在用于被动结构时,主动结构中的间接宾语变为主语时,直接宾语仍然保留在谓语后面；直接宾语变为主语时,间接宾语前通常加上介词for/to
有些动词后跟不带to的不定式作宾语补足语,但改为被动结构后要加上“to”.例如
We heard him sing in his room just now.
---He was heard to sing in his room just now.