Question

have的用法 什么时候用have done 什么时候用have to do. 什么情况下动词开头用

Answer 1

1. 在表达“我已经完成某件事情的时候”have done 是现在完成时的动词表达形式.比如：

I have read three novels by now. 到现在为止,我已经读了3本书了.

2. have to do 表示“不得不、必须做某事,客观上决定必须做某事”过去时是 had to do

e.g. I have to finish reading another three books to complete my reading plan.我还要再读3本书才能完成我的读书计划.

3. doing 用在句首有这样几种情况

1） doing （动名词）做主语时. e.g. Reading is my favorite hobby.

2) doing (现在分词）短语,在句中作状语,表时间、伴随、原因等.

E.g. Finishing doing my homework, I began to watch tv.