6. I find it hard to believe that he passed the exam.
7. You play tennis better than I do.
8. It's 2 years since I last went to the dentist's.
9. They're such easy questions that everyone can answer them.
10. If I were you, I would take the train.
11. My father doesn't play football anymore.
12. It is easy to learn English.
13. If you leave the lights on all night, you will waste electricity.