Use the infinitive with or without to.
1. I had better (not/smoke).
2. I forgot (do) my homework yesterday.
3. I heard them (come) late at night.
4. You won't be able (go) to the party if we dont find the keys.
5. I couldn't go to to the cinema because I had (look) after my little sister.
6. Susan would rather (study) for her exam tomorrow.
7. Can you tell me how (get) to the bus stop?

1. I had better not smoke. (?)2. I forgot to do my homework yesterday.3. I heard them come late at night.4. You won't be able to go to the party if we don't find the keys.5. I couldn't go to to the cinema because I had to look after my little sister.6. Susan would rather study for her exam tomorrow.7. Can you tell me how to get to the bus stop?