① 英語序數(shù)詞表順序,基數(shù)詞表總數(shù).th、st、nd、rd是由基數(shù)詞變?yōu)樾驍?shù)詞時需加的詞尾,當(dāng)然,要因詞而異!其中,st用于指代first；nd指代second；rd指代third.例如：
one－－first two－－second three－－third
four－－fourth five－－fifth six－－sixth
seven－－seventh eight－－eighth nine－－ninth
ten－－tenth eleven－－eleventh twelve－－twelfth
twenty－one －－ twenty-first
twenty-two －－ twenty-second
twenty－three －－ twenty-third
② 1.73rd seventy-third
2.31st thirty-first
3.42nd fourty-second
4.18th eighteenth
5.100th one hundredth