1. Do I have to fill in any forms?
-> Is it necessary for me to fill in any form?
2. I cannot find out the truth because I don’t hear the two of them talking.
3. It is necessary that I post this letter tonight.
-> I need to post this letter tonight
4.This food is so good that I’m going to have some more.
-> This is such as a good food that I'm going to have some more
5. “Please don’t smoke in the house.” she said to us.
->She requested us not to smoke in the house.
6. “Why don’t you mention the problem now?” I asked them.
-> I asked them why had not you mention the problem before
7. You are unfit because you don’t do enough exercise.
-> If you weren't unfit , you would have do more exercise
mình còn câu 2 nữa thoi ạ sorry