小学英语中的基数词和序数词定义表示数目的词是基数词。构成最基本的数词如下: 1 one, 2 two, 3 three, 4 four, 5 five, 6 six, 7 seven, 8 eight, 9 nine, 10 ten, 11 eleven, 12 twelve, 13 thirteen, 14 fourteen, 15 fifteen, 16 sixteen, 17 seventeen, 18 eighteen, 19 nineteen, 20 twenty, 30 thirty, 40 forty, 50 fifty, 60 sixty, 70 seventy, 80 eighty, 90 ninety,100 a hundred, 1,000 a thousand,1,000,000 a million, 1,000,000,000 a billion. 基数词 1-12 是独立单词，需逐个记忆。基数词13 - 19是个位数词的词干后加-teen 构成。其中thirteen, fifteen, eighteen变化不规则。基数
