怎么能区分to do ,doing、、不定式，动名词的用法？

最简单来讲。
to do(不定式)：表目的。例：I want to buy coffee, because I feel sleepy.
doing(动名词):1.表示正在进行的状态,动词一般是可以持续的。例：I am watching TV/ buying coffee/ crying/driving。2.独立主格或者伴随这两种语法现象，会把动词加ing。例: Hearing from her, I feel relaxed.(收到她的来信，我就安心了) 。

你先死记住这些重要的，加do to do ding的词组

make sb. do sth.
let sb. do sth.
decide to do
look forward to doing(to作介词)
need to do
want to do
begin/start to do
remember to do/doing
forget to do/doing
It takes sb. some time to do
why not do?
why don't you do ?
what/how about doing?
hate to do
like/love/enjoy doing
be sure to do
can/could/must/may/might do
seem to do
stop to do/doing
learn to do
keep doing
why not do?(提建议的句子一般用do)

至于不定时to do：有时也可省略前面的to，在谓语动词之后时。
to do一般都是讲还没有做的，将要去做的，带有目的性
而一般加doing的都是已经做过的事
比如：remember记住
remember doing 是指记住做过某事
remember to do 是指记着将要做某事

希望对你有帮助嘿！

看这个网页，有很详细的解答：

http://zhidao.baidu.com/question/61351831.html

I want to do you.
I want to be doing you right now.