Réponse:

2) you must not loose time

You should stop spending whole day on your phone.

I want you to write your homeworks at first.

3) You must not use anyone's e-mail for your business!

You should create your own e-mail account.

I don't want you to use my e-mail

4) You must not reveal these kind of things there

I don't think that you should do it

I would say no that's not safe!

5) You must not spend too much many on dumb things which you won't use.

You should try it, i think it's good.

No i don't want you to use it, i tried and it's not safe

6) And then you'll be able to spend more time on it? No, you must not do that.

I don't think you should, if you use it regularly it will damage your eyes

No, i don't want, it must stay where it is now!