.1 stop doing/to do
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。
.2 forget doing/to do
forget to do 忘记要去做某事。 (未做)
forget doing 忘记做过某事。(已做)
The light in the office is stil on. He forgot to turn it off.
办公室的灯还在亮着,它忘记关了。(没有做关灯的动作)
He forgot turning the light off.
他忘记他已经关了灯了。 ( 已做过关灯的动作)
Don’t forget to come tomorrow.
别忘了明天来。 (to come动作未做)
典型例题
---- The light in the office is still on.
---- Oh,I forgot___.
A. turning it off B. turn it off C. to turn it off D. having turned it off
答案:C。由the light is still on 可知灯亮着,即关灯的动作没有发生,因此用forget to do sth.
而forget doing sth表示灯已经关上了,而自己忘记了这一事实。此处不符合题意。