Author: A True Story, r-Controlled Vowels ar, ir, ur

1. turns
2. first
3. herds
4. learn
5. purr
6. third
7. earn
8. nurse
9. perch
10. girls
11. firm
12. word
13. world
14. serve
15. worth
16. he'd
17. wasn't
18. didn't 
19. perfect
20. Thursday