Write the correct form of each verb in brackets.

1. If Lan (want) ______ to focus on her homework, she should turn off the TV.

2. I don't know who (ask) ______ for advice about my future career.

3. If he (continue) ______ making noise, he must leave immediately.

4. They are wondering what (buy) ______ for their grandmother on her birthday.

5. We can make the air in the city cleaner if we (not use) ______ our cars as much.