I didn`t finish writing my test.和Amy started skating when he was nine.的动词finish、start后为什么要

问题描述:

I didn`t finish writing my test.和Amy started skating when he was nine.的动词finish、start后为什么要
跟动词的ing形式?
谢谢······

这个是习惯用语,或者可以说是固定搭配,可是有些动词后跟不定式和后面跟ing形式意思会不同,像forget to do sth 是忘记了要做的事,特指这件事没有做过.儿forget doing sth就是忘记了做过某事,这件事是做过的.多积累吧,