It's two years since I last spoke to her

1. It's two years since I last spoke to her. 
-> I haven't .....
2. "How long have you waited here'' he asked me.
-> he asked me...
3. Minh doesn't read many english books because he does't have time.
-> If Minh...
4. Students will play more active roles in the classroom. 
 -> More active roles....