数 词
数词定义  数词是表示数目多少或先后次序词,有基数词和序数词两种。 表数量数词叫基数词，如one, two, three,… 表次序数词叫序数词，如first, second, third, fourth,   fifth,...
基数词组成1）1~12单独记 one, two, three, four, five, six, seven, eight, nine, ten, eleven, twelve2)13~19词尾为-teen：thirteen, fourteen, fifteen, sixteen, seventeen, eighteen, nineteen3)20~90逢整十词尾为-ty：twenty, thirty, forty, fifty,...4)21~ 99在十位数和个位数之间加连字符组成，如：  73 seventy-three, 88 eighty-eight