1. deer - deer
2. species - species
3. fish - fish
4. bison - bison
5. sheep - sheep
6. trout - trout
7. salmon - salmon
8. wolf - wolves
9. leaf - leaves
10. life - lives
11. shelf - shelves
12. wife - wives
13. half - halves
14. scarf - scarves
15. mouse - mice
16. foot - feet
17. tooth - teeth
18. man - men
19. child - children
20. goose - geese
21. woman - women.