Prefixes pre- and pro-

1. prevent 

2. program

3. predict

4. project

5. pretend

6. process

7. prefer

8. promise

9. previous

10. protect

11. property

12.  propose

13. precede

14. proceed

15. Pronunciation   

16. Professional   

17. pretest

18. preview

19. proclaim

20. progress

Extra Credit Words: a. hypothesized  b. St. Patrick's Day