表⽰“多少”和“第⼏”的词，叫数词。数词分为基数词和序数词两种。
1)基数词：在⼗位数词和个位数词中间加上连字符 “ - “ 。如： 21 twenty -one‘基数词三位以上的数词， 在百位和⼗位之间，⼀般要⽤连词\"and “。 如： 132 one hundred and thirty-two.
表⽰”万“的词英语中没有。如1万可⽤10千来表⽰。 ten thousand. 30万可⽤ three hundred thousand 来表⽰。 基数词的⽤法：
1.编号的事物⽤基数词： 如：Lesson Five， Room 101 2.表⽰”年，⽉，⽇“ 时⽤基数词。
3.表⽰ “⼏点钟， ⼏点过⼏分” ⽤基数词。 It is two to two. 现在是两点差两分。
4.加减乘除⽤基数词。 One plus two is three.⼀加⼆等于三。Eight minus four is four. ⼋减四等于四。 Two times two is four.⼆乘⼆等于四.Ten divided by two is five.⼗除⼆等于五。 5表⽰百分数⽤基数词.
Thirty percent of them is water. 它们当中有30%的⽔。
6.表⽰分数时，分⼦数字⽤基数词， 但分母要⽤序数词， 如分⼦不是1，序数词要⽤复数形式。 One-fifth of the books are mine. 三分之⼀的书是我的。 Three-tenths of water is disappeared. ⼗分之三的⽔不见了。 2)序数词：表⽰数⽬顺序的词⽤序数词。
1.序数词1━19 除第⼀，第⼆，第三，第五，第⼋，第九， 第⼗⼆变化不规则外， 其余均由在基数词后加上 -th。 2.⼗位整数的序数词的构成⽅法是， 是将⼗位整数基数词的词尾 -y 变成 i 再加 -eth。 3.⼏⼗⼏的序数词，只是把个位数变成序数词， ⼗位数不变。
4.第⼀百以上的多位序数词 由基数词的形式变结尾部分为序数词形式来表⽰。 one hundred and twenty-first ，one thousand，three hundred and twentieth 5.序数词的缩写形式 有时，序数词可以⽤缩写形式来表⽰。主要缩写形式有。
first--lst second--2nd third--3rd fourth--4th sixth--6th twentieth--20th twenty-third--23rd 其中lst，2nd，3rd为特殊形式，其它的都是阿拉伯数字后加上th。
6.通常前⾯要加定冠词 the；但是如果序数词前出现不定冠词a或an时，则表⽰“再”，“⼜”. We’ve tried it three times．Must we try it a fourth time？
7.基数词也可以表⽰顺序。只需将基数词放在它所修饰的名词之后(名词需⼤写) 即可，不需要添加定冠词。 the first lesson-Lesson One ，the fifth page-Page 5， the twenty-first room-Room 21 练习
( )1. I‘ve read ______ sports news about the F1 race today. A. two B. pieces C. two pieces D. two pieces of
( )2. During World War II， a Jewish（犹太）lady was protected by a local family in Shanghai in her ______. A. fifties B. fifty C. fiftieth D. the fiftieth
( )3. The river through our city， which is about _________， is clean again.
A. 6000 meters long B. 6000-metres-long C. 6000-metre-long D. 6000 meter long
( )4. I study in Yu Cai Middle School. There are two ____students in our school. A. thousand B. thousands C. thousand of D. thousands of ( )5. They said they would have holiday.
A. a two-month B. two months C. two-months D. two-month’s ( ) 6.-When was the PLA founded？ -It was founded on ____. A. July 1. 1921 B. October 1.1949 C. May 1.1922 D. August 1.1927
( ) 7. In the past two years， many tall buildings have been built in our city. The tallest is an that stands in the centre. A. 80-floor building B. 60-floor building C. 80-floor buildings D. 70 floors building
( )8.The number of people invited ____ fifty， but a number of them _____absent for different reasons. A. were ； was B. was ； was C. was ； were D. were ； were\\ ( )9.- How soon will you finish your work？ -In about _______. A. one and a half month B. one month and a half C. one and half a month D. a month and half
( )10.-Would you like some fruit， madam？ -Oh， yes. _______， please. A. 5 kilo bananas B. 5 kilos of bananas C. 5 kilo of bananas D. 5 kilos of banana
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