2. Man – men 2.男人

3. Datum – data 3.数据

4. Criterion – criteria 4.标准

5. Medium – media 5.媒质

6. Foot –feet 6.脚，英尺

7. Tooth – teeth 7.牙齿

8. Mouse – mice 8.老鼠

9. Sheep – sheep 9.羊

10. Crisis – crises 10.危机

11. Stimulus – stimuli 11.刺激

12. Thief – thieves 12.贼，小偷

13. Wolf – wolves 13.狼

14. Leaf – leaves 14.叶子

15. Person – people 15.人

16. Life – lives 16.生命

17. Goose – geese 17.鹅

18. Thesis - theses 18.主题

19. Potato – potatoes 19.土豆

20. Cactus – cacti 20.仙人掌