Rewrite the following sentences so that the meanings stay the same

Rewrite the following sentences so that the meanings stay the same.
1.She eats more chocolate than I.
 I
2.Vinh keeps forgetting his homework
It's
3.Keeping the enviroment clean is very important.
It's
4.No one helped Lan to do the homework.
Lan 
5.It's three years since I last spoke to her.
I haven't
6.Tam doesn't type as fast as she used to.
Tam used 
7.How long is it since you used the car?
When
8.We started living here 15 years ago.
We have
9.Let's meet inside the center,at the cafe corner?
How 
10.Nam is very strong,he can do heavy work.
Nam is strong