完成式不定词 | 英语文法指南 | ef-九游官网下载
完成式不定词多数会出现在第三类条件句，用作完成条件式的一部分；但完成式不定词也可用在其他句型上。完成不定词的构成为：
to have 过去分词
如同现在式不定词，有些时候必须用上不带 to 的被动语态不定词，因此 to 会被省略掉。这种情况会发生在多数情态助动词后，以及用在其他使用零不定词的地方。
举例
- he pretended to have seen the film.
- before i turn 40, i want to have written a book.
- i would like to have been to the taj mahal when i was in india.
- if i had known you were coming i would have baked a cake.
- someone must have broken the window and climbed in.
- that man may have noticed the bank robbers' getaway car.