使用现在分词的几种情况
1.进行时态。如：
He is playing computer games in the room.
They were chatting in the sitting room at nine o'clock last night.
简单的来说，现在分词用作进行时态时，即在be动词（am,is,are或was,were）后面加doing，但需要注意的是，有时be动词后面接动词的被动式，这就需要我们对于语境的正确把握。
2.there be结构。如：
There is a girl dancing on the stage.
意为“有……在做……”，其实这一结构也可以看做第一种情况的一种。
3.介词后面。如：
Thanks for helping me.
Are you good at playing basketball.
4.以下结构中：
enjoy doing sth 乐于做某事
finish doing sth 完成做某事
feel like doing sth 想要做某事
stop doing sth 停止做某事
forget doing sth 忘记做过某事
go on doing sth 继续做某事
remember doing sth 记得做过某事
like doing sth 喜欢做某事
keep sb doing sth 使某人一直做某事
find sb doing sth 发现某人做某
have fun doing sth 做某事充满乐趣
have problem doing sth 做某事有困难
hear/watch sb doing sth 看到/听到/观看某人做某事
try doing sth 试图做某事
need doing sth 需要做某事
prefer doing sth 宁愿做某事
mind doing sth 介意做某事
practice doing sth 练习做某事
be busy doing sth 忙于做某事
can't help doing sth 禁不住做某事
miss doing sth 错过做某事
5.to do vs. doing
(1) forget to do sth 忘记要做某事（还未做）
forget doing sth 忘记做过某事（已做了）
例： He forgot to turning the light when he left the classroom last night. (他昨晚离开教室时忘记关灯了。)
He forgot turning the light when he left the classromm last night. (他忘记他昨晚离开教室时已经把灯关了。)
(2) remember to do sth 记得去做某事（还未做）
remember doing sth 记得做过某事（已做了）
例： Remember to go to the post office after school. (放学后记得去趟邮局。)
I remember going to the post office after schoool. (我记得我放学后去过邮局了。)
以上两个单词都有两种用法，要牢记其不同用法的不同意思，结合语境正确应用。
下面， 让我们做一个题感受一下吧
——The light in the classroom is still on.
——Oh, I forgot _________ .
A. turning it off B. turn it off C. to turn it off D. having turned it off
答案与解析：由第一句可知灯还亮着，那么灯是忘记关了。而forget to do sth意为忘记要做……，所以应当选C，忘记关灯了。
