(四)数词
1. 数词分类：
分类 | 在句中充当的成分 | 例词 |
基数词 | 主语、表语、宾语、定语、同位语 | one, eleven, fifty |
序数词 | 主语、表语、宾语、定语、同位语、状语 | second, eighth, fortieth |
2．基数词的构成及用法：
类型 | 构成方法 | 例词 |
1-12 | 单独的词 | one, two, three, four, five, six, seven, eight, nine, ten, eleven, twelve |
13-19 | 在3-9的词尾加上“-teen” | thirteen, fourteen, fifteen, sixteen, seventeen, eighteen, nineteen |
20,30,40-90 | 以“-ty”结尾 | twenty, thirty, forty, fifty, sixty, seventy, eighty, ninety |
100,1000,1000,000, 1000 000 000, | 百，千，百万，十亿都有具体量词 | one/a hundred, one/a thousand, one/a million, one/a billion |
21-99 | “几十”和“个位”之间用连字符“-” | twenty-three,forty-eight |
101-999 | “百位”后“十位”前加“and” | 826: eight hundred and twenty-six |
1,000以上 | 先从右向左每三位数加一逗号，从右向左第一个逗号为thousand,第二个为million,第三个为billion,然后每三位为一单位从左向右读。 | 1，234，567，892: one billion, two hundred thirty-four million, five hundred sixty-seven thousand eight hund red and ninety-two |
3.序数词的构成：
类 型 | 构成特点 | 例词及缩写式 |
one, two, three | 单独记忆 | first (1st), second (2nd), third (3rd) |
four～nineteen | 在基数词尾加-th | fifth (5th), ninth (9th), twelfth (12th) |
-ty结尾的词 | 把y→ie，在基数词尾加-th | twentieth (20th), fiftieth (50th), fortieth (40th) |
以1～9结尾的多位数 | 变个位数为序数词即可 | twenty-first (21st), ninety-ninth (99th) |
hundred, thousand, million, billion | 在基数词尾加-th即可 | hundredth (100th) thousandth (1,000th) millionth (1,000,000th) billionth (1,000,000,000th) |
4.序数词的用法：
序号 | 用法特点 | 举 例 |
1 | 前面要加the | He’s always the first to get to meeting-room. |
2 | 前面用a/an表“又一，再一” | He’d better try a fourth time. |
