基数词 序数词
1 one first
2 two second
3 three third
4 four fourth
5 five fifth
6 six sixth
7 seven seventh
8 eight eighth
9 nine ninth
10 ten 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