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。
