例如：I had no choice but to wait.
②当作宾语的不定式后跟有宾语补足语时，通常要用形式宾语it代替不定式，并将真正的宾语不定式置于宾语补足语之后
例如：I find it difficult to learn Japanese well.
4、不定式作宾语补足语
例如：Who taught you to drive?
5、不定式作定语
例如：I have a question to ask you.
注意：有的名词（如way, chance, right等）后用作不定式可换成of doing sth.
如：It is the best way to do (of doing) it.
但是以下名词后接不定式作定语时通常不能换成of doing sth.
attempt  courage  decision  effort  fortune  failure  invitation  wish
6、不定式作状语
例如：I went to France to learn French.