first 1st second 2nd twenty-first 21st one hundred and first

first 1st second 2nd twenty-first 21st one hundred and first first,1st second,2nd 数字后的st/nd什么意思 1－100的序数词分为四1－100的序数词分为四个类.1、第一类 first (1st) 第一 second (2nd) 英语的序数词怎么写?twenty-first,twenty first,21th,21st哪个对哪个更常用? first 和 1st 是否通用? 英语 1st 表示的是first 还是the first?in the 1st centry May,21st读做May twenty-first,人教版录音带这么读,我们以前这么读May the twenty-f first genocide of the 21st century."翻译 1st是first的缩写怎样翻译 十月一日是October first还是October 1st? first 和 1st 是否通用?也就是说,能用first的场合是否都可以用1st 替代? May 1st如何说?是May the first 还是May first?