1. They have göne to the zoo  for 2 Weeks.
=>It's 2 weeks since they have göne to the zoo
2. Nam has never given me money before.
=>This is the first time Nam has  given me money 
3.When did you buy this dictionary ?
=>How long have you bought this dictionary?
4.1 haven't met him since I left school.
=>I last met him since I left school.
5. She prefers watching T.V to listening to music.
=>She would rather watch T.V than listen to music.
6.Tam doesn't type as fast as she used to.
-Tam used to type faster than she does now. 
7.How long is it since you used the car?
-When did you use the car?
8.We started living here 15 years ago.
-We have lived here for 15 years.
9.Let's meet inside the center ,at the cafe corner?
-How about meeting inside the center ,at the cafe corner?
10.I've never eaten this kind of cake.
-It's the first time I I've  eaten this kind of cake.
11-Hoa loves reading the story.
->Hoa enjoys reading the story.
12- don't like to watch TV every night.
->l dislike watching TV every night.
13-Tea is warm. I can drink it.
->Tea is  my favourite drink
14. The water was so cold that the children couldn't swim in it
->The water wasn't warm enough for children to swim in it
15.It isn't necessary for you to set off early
->you don't have to set off early

-Answer by Nun8119-