关于英语句型的问题？

Question

什么时候该用不定式？什么时候该用动名词？
请详细说明，最好带几句话来解释/Thank you!

Answer 1

作宾语时，不定式表示将要发生的动作；动名词则表示已经发生或正在发生的动作。例如：
I forgot turning off the lights before I left the classroom. (忘记关灯了，过去的动作）
Don't forget to turn off the lights before you leave the classroom. (不要忘记去关灯，将来的动作。）

Answer 2

Sometimes we call a verb followed a preposition 'to'for indeterminate form,
For example:
I (try to get) responses from zhidao.baidu.com,
But it seems no proper answers, which made me sad.

Here the 'try to' is a indeterminate form.(you plain to do it)

A indeterminate form stands for an 'Action' which will happen expected，while the gerund is an 'Action' that you have done.

Questions(finish them yourself,you will know what's the differences between them):

Q1 - I tried ____ a ticket, but they had all sold out.
A:to get B:getting
Q2 - I tried ____ to her personally, but I couldn't persuade her.
A:to speak B:speaking
Q3 - Jon, I have some bad news- I regret _____ that your application has been unsuccessful.
A:to say B:saying
Q4 - She stopped ____ when she got married.
A:to smoke B:smoking
Q5 - I regret ____ so rude last night.
A:to be B:being
Q6 - She went on _____ the CEO a few years later.
A:to become B:becoming
Q7 - Remember ____ her at lunchtime.
A:to call B:calling
Q8 - I don't remember ____ the cooker off before I left.
A:to turn B:turning
Q9 - We can't go on _____ like this- we must find a better way.
A:to work B:working
Answers(A B A B B A A B B),What's grade you get!