小学英语语法常用术语（小学英语语法数词）

小学英语语法常用术语（小学英语语法数词）twenty→twentieth forty→fortieth ninety→ninetieth （3）以y结尾的十位整数，变y为ie再加th eg：four→fourth thirteen→thirteenth （2）不规则变化 one→first two→second three→third five→fifth eight→eighth nine→ninth twelve——twelfth

一基数词

1~12	13~19	20~90	100~1000000000
onetowthreefourfivesixseveneightnineteneleventwelve	thirteenfourteenfifteensixteenseventeeneighteennineteen	twentythirtyfortyfiftysixtyseventyeightyninetytwenty-oneninety-nine	百a/one hundred千one thousand万ten thousand十万one hundred thousand百万one million千万ten million亿one hundred million十亿one billion

二序数词

1.序数词的构成

（1）一般在基数词后加th

eg：four→fourth thirteen→thirteenth

（2）不规则变化

one→first two→second three→third five→fifth eight→eighth nine→ninth twelve——twelfth

（3）以y结尾的十位整数，变y为ie再加th

twenty→twentieth forty→fortieth ninety→ninetieth

（4）从二十一后的“几十几”直至“几百几十几”或“几千几百几十几”只将个位的基数词变为序数词。

twenty-first two hundred and forty-fifth

2.序数词的用法

（1）序数词作定语时，一般要与定冠词或物主代词连用。

eg：Tom is their second son.

He is the first one to come here.

（2）序数词有时可与不定冠词连用，表示数量上“又—” “再一” 。