A.
首先why not ,why don't you后面加动词原形do.固定搭配.
然后finish doing sth.结束;做毕 .
英文释义：When you finish doing or dealing with something, you do or deal with the last part of it, so that there is no more for you to do or deal with.
例句：
As soon as he'd finished eating, he excused himself...他一吃完就告辞离开了.
Mr Gould was given a standing ovation and loud cheers when he finished his speech...
古尔德先生结束演讲后,全场起立鼓掌并热烈欢呼
不像stop,remember,begin即可加doing,又可加to do,finish没有finish to do的用法.