Give the noun form of:
1. to use
2. to remove
3. to thread
4. to hold
5. various
6. headless
7. to repeat
8. to adjust
9. to require
10. to wish
11. to protect
12. easy
13. to function
14. to turn
15. to receive
16. to explain
17. to describe
18. to rivet
19. to lock
20. to weld