Put the correct form of the verbs in the brackets: Someone is knoking at the door. I (open) it.

Ex 13. Put the correct form of the verbs in the brackets
1. Someone is knoking at the door. I (open) it.
2. They (build) a new theatre here in 2010?
3. I (not,come) back here until next month
4. What you (do) if you go to England?