finish doing something.
Did 后面动词原形 就是 finishDid 后面动词原形只能跟一个吗？Did you forget to do your homework?这里 后面就有两个动词原形 forget和 do看你如何理解了， forget to do something 毕竟是个固定短语。Did you finish doing your homework中doing在这里是不是动名词是的。