我给你列举下吧

1 基数词one 序数first

2. two基数/second

3.three/thrid

4.four /fourth

5.five/fifth

6.six/sixth

7.seven/sevendth

8.eight/eighth

9.nine/ninth

10ten/ tenth

11.eleven /eleventh

12 twelve/twelfth

13.thirteen/thirteenth

14.fourteen/fourteenth

15.fifteen/fifteenth

16.sixteen/sixteenth

17.seventeen/seventeenth

18.eighteen/eighteenth

19.nineteen/nineteenth

20.twenty/twentieth

21.twenty-one 基数/twenty-first序数

看懂了么，一次类推了基数在前面，后面是序数的表示