Complete the sentences with the correct forms of the verbs.
1. If I clean (clean) the house, my parents will give (give) me some extra money .
2. I ........ (phone) Mike if he ...... (not arrive) before 10 o'clock.
3. If you ..... (speak) very fast, they ...... (not understand) you.
4. If Marco ...... (phone) tonight, ..... you ....... (tell) him I'm at Sabina's house? .
5. Your parents ....... (not know) if you ..... (not tell) them.