题目内容：

动词不定式to have seen怎么替换?
是将have换成be还是being,或者干脆换成that they have seen?整句是这样,They claim to have seen monsters in the sea.我需要解释怎么换,为什么.

优质解答

claim做及物动词,只有如下两种用法
claim sth.
claim+that从句
没有claim to do的用法
所以应换成that they have seen