是英语中的序数词
onefirst 1st
twosecond2nd
threethird 3rd
four fourth4th
five fifth 5th
sixsixth 6th
sevenseventh 7th
eighteighth8th
nine ninth 9th
tententh 10th
注意:11、12与其他1、2结尾的序数词缩写不同
eleven eleventh 11th
twelve twelfth12th
其他的都可参照1st、2nd、3rd
如21st、23rd等等