数词分为两大类：基数词和序数词。

基数词：one, two, three, four, five, six, seven, eight, nine, ten。

序数词：first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth.序数词前通常用the。

基数词变序数词规律：

123特殊记，8去t,9减e；

ve要用f替，然后再加th；

整十变化需注意，把y去掉加ie；

如果遇到几十几，只变个位就可以。

数词hundred、 thousand、 million不用复数，如：

three thousand

“复数+of”可表示数百、数千、数百万，如：

thousands of trees（数千棵树）

在表达年龄时，注意以下表达法：

He is six years old.（其中year须用其复数）

He is a six-year-old boy.（其中year不用复数）

分数：由基数词和序数词构成，分子用基数词，分母用序数词，当分子超过“1”时，分母用复数，如：

two thirds=2/3 three fifths=3/5

练习题

1.They have learned about______in recent years.

A.several hundreds English words

B.hundreds of English words

C.hundred of English words

D.several hundred English word

2.Nancy is_____girl.

A.a eighteen-year-old

B.an eighteen-years-old

C.a eighteen-years-old

D.an eighteen-year-old

3.Nowadays_____of business letters are written in English.

A.two third

B.two thirds

C.two three

D.second three

5.My pet dog is______(three) years old.

6.My grandmother lives on the______(ten) floor. oMoXYbYiSbuTCgAmV1iUKzkuDhnuhS+NTiu7HTTvEHicmR/pw8tRXLvTAmsHL5Wa