怎样背基数词和序数词答:3、21-29的基数词:twenty-one, twenty-two, twenty-three, twenty-four, twenty-five, twenty-six, twenty-seven, twenty-eight, twenty-nine.4、20-90的基数词:twenty, thirty, forty, fifty, sixty, seventy, eighty, ninety.5、100 基数词 :hundred.6、1-10的序数词:first. second. ...