stop to do 停止,中断做某事后去做另一件事。
stop doing 停止做某事。
They stop to smoke a cigarette.  他们停下来,抽了根烟。
I must stop smoking..  我必须戒烟了。
典型例题
She reached the top of the hill and stopped ___ on a big rock by the side of the path.
A. to have rested B. resting  C. to rest D. rest
答案:C。由题意可知,她到了山顶,停下来在一个路边的大石头上休息。因此,应选择"stop to do sth. 停下来去做另一件事"。而不仅仅是爬山动作的终止,所以stop doing sth.不正确。
stop doing/to do: http://insuns.com/article/15469-1.html