20的序数词,还要30,40,50,60,70,80,90,100的

first second third forth fifth sixth seventh eighth ninth tenth eleventh twelfth 13~19在后面加th 20 30 40 50 60 70 80 90 也一样

1:first
2:second
3:third
4:fourth
5:fifth
6:sixth
7:seventh
8:eight
9:ninth
10:tenth
11:eleventh
12:twelfth
13:thirteenth
14:fourteen
15:fifteen
16:sixteenth
17:seventeenth
18:eightteenth
19:nineteenth
20:twentiety
30:thirieth
40:fortirth
50:fiftieth
60:sixtieth
70:seventieth
80:eightieth
90:ninetieth
100:hunderdth
加的规律是：
在基数词后加th
（first,second,third除外）
如果是t结尾,那么加h
如果是y结尾,那么把y改为ie,再加th
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