表示数目的词称基数词。15 fifteen，几百几千不加s，242 two hundred forty-two，5058 five thousfifty-eight，9，600，000 nine million six hundred thousand
6+8 = 14 Six plus eight is fourteen.
9-7 = 2 Nine minus seven is two.
7X5 = 35 Seven times five is thirty-five.
8÷4 = 2 Eight divided by four is two.
He died in his fifties.
1700 seventeen hundred
1814 eighteen fourteen
Number six， line 4， page 19， Bus(No.) 332， Platform (No.) 5， Room 101
A one-month-old baby can recognize its mother by smell.
This eleven-month-old baby can speak a few words.
(The baby is eleven months old.)
The teacher asked us to write a four-thousand-word essay as our homework.
(There are four thouswords in the essay.)
表示顺序的词称为序数词。如first， second， third， fourth， ninth， twenty-first， forty-fifth等。
序数词可以用来表示日期和世纪。May the first / the first of May (5.1) ， August the eighth / the eighth of August (8.8) ， the twentieth century， the twenty-first century
The first of October is our National Day.
She was the third to arrive.
They'll have to do it a second time.
Shall I ask him a third time?
When he sat down ， a fourth man rose to ask.