to作为动词不定式的标志的时候 后面接do
to作为介词的时候 后接doing 只要记住接doing 的情况就可以了
look forward to doing
be used to doing
get down to doing
lead to doing
as to doing
prefer doing to doing
lead to
object to初高中阶段 出现频率比较高的就这些了