Ответ:
1. You must ask somebody to help you in this work.
2. If I have some free time, I shall go somewhere tonight.
3. Have you heard anything about our plan?
4. Did anybody see this film yesterday?
5. Did you say anything? - No, I said nothing.
6. I know nothing about it, and he doesn't know anything about it either. Nobody knows about it.
7. Everybody is here. We can open the meeting.
8. She knows all about it, but she doesn't want to tell us anything.
9. You must do something to improve your English.
10. Ask somebody to help you in this work.
11. Everybody likes this song. No wonder, you can hear it everywhere.
12. The other day we went to see our friends, but nobody was at home.
13. There is something important in the letter.
14. Victor will go nowhere because he feels unwell.
15. Please give me something interesting to read.
16. Will anybody go to the library right after classes?
17. I'm sure you can get this book somewhere.