Here are the sentences completed with the correct forms of the verbs in brackets:

1. I don't mind **eating** meat, but I'd rather **eat** fish.
2. Doctors hope **to find** a cure for cancer.
3. Teenagers enjoy **surfing** the Internet.
4. I promise **not to be** late again.
5. I forgot **to phone** you yesterday.
6. Before **answering** the questions, please read the text carefully.
7. I used to **go** to school on foot when I was a primary student.
8. I have just invited my friends **to have** dinner in my house.
9. He wants me **to tell** him the truth.
10. **Adding** fruit and vegetables every day is necessary.
11. The doctor advised him **to give up** smoking.
12. The boy seems **to be** very polite.
13. I can't bear **waiting** for people when it's raining.