4、分数的表达方式
1)分子用基数词，分母用序数词，分子大于1时，分母用复数。如：one-third三分之一，three-sevenths七分之三。
2)分子与分母之间加in, 分子在前，分母在后，分子分母都用基数词。如：one in ten 十分之一，five in eight八分之五。
3)分子与分母之间加out of , 分子在前，分母在后，分子分母都用基数词。如：one out of ten十分之一，five out of eight八分之五。
3、大约数的表示方法
1)用ten、dozen、score、hundred、thousand、million等数词的复数后加of短语来表示几十、几百、上千、成千上万等大约数概念。如：
The little boy buys dozens of pencils every term.
Thousands of people died in the earthquake.
Every year tens of thousands of people go to work in Guangdong Province.
2)用、less than、under、below、almost、nearly、up to 等来表示小于或接近某数目。如：
He is good at English, so he can finish the paper in less than two hours.
3)用more than、over、above、beyond、or more等来表示超过或多于某个数目。如：
Peking University has a history of more than 100 years.
4)用or、or so、about、around、some、more or less等表示在某一数目左右。如：
About 50 people were present at that time.
5)用to、from … to…、between … and表示介于两数词。如：
His salary rises from 20 dollars a week to 35 dollars a week.
6)注意事项：dozen、score、hundred、thousand、million作数词表示确切数量时，不用复数。如：three score, five dozen, seven million等。
2、倍数的表达方式
一般情况下我们用以下三种倍数表达方式：
1)倍数用在as + 形容词 / 副词(原级)+ as结构之前。如：
They have three times as many cows as we do.
2)倍数放在形容词或副词的比较级之前或by + 倍数用在比较级之后。如：
This rope is four times longer than that one.
They produced more products in 2001 than those in 2000 by twice.
3)倍数用在表示度量名词前，其基本结构为：倍数 + the + size / length / weight … + of + 表示比较对象的名词，也可用于倍数 + what引导的从句中。如：
This room is three times the size of that one.
The college is twice what it was 5 years age.
You can’t imagine that rats eat 40 to 50 times their weight.
1、序号表示法
1)单纯的序号，可在基数词前加number,简写为No.。如：No.1第一号
2)事物名词的序号表达法有什所不同：
①对于一些小序号可有序数词也可用基数词表达，形式分别为：the +
序数词 + 名词；名词 + 基数词。如：第一次世界大战可以表示为the First World War或World War One。
②对于一些大序号我们通常只用一种表达法，即名词 + 数词。如：501号房间表示为Room 501, 538路公共汽车表示为Bus 538。
③可用a / the + number + 基数词 + 名词。如：a No.5 bus一辆五路公共汽车，the No.8 bus那辆8路公共汽车
3. that代替前面提到的同类事物中特指的一个。该事物既可以是可数名词也可以是不可数名词,要有后置定语,但不可以有前置修饰语。
[典型例题]
Few pleasures can equal ________ of a cool drink on a hot day.
A. some B. any C. that D. those
答案: C
数词
表示数目多少或顺序多少的词叫数词，数词分为基数词和序数词。表示数目多少的数词叫基数词；表示顺序的数词叫序数词 一、基数词 1.基数词写法和读法：345 three hundred and forty-five； 2.基数词一般是单数形式，但下列情况，常用复数： a. 与of 短语连用，表示概数，不能与具体数目连 用，如scores of people 指许多人； b. 在一些表示"一排"或"一组"的词组里； 如：They arrived in twos and threes. 他们三三两两的到达了。 c. 表示"几十岁"； d. 表示"年代"，用 in +the +数词复数；
e. 在乘法运算的一种表示法里，如：3 x 5 = 15 Three fives is (are) fifteen. 二、序数词 序数词的缩写形式： first---1st second---2nd thirty-first---31st 三、 数词的用法 1.倍数表示法 a. 主语+谓语+倍数(或分数)+ as + adj. + as I have three times as many as you. 我有你三倍那么多。 b. 主语+谓语+倍数(分数)+ the size (amount，length…) of… The earth is 49 times the size of the moon. 地球是月球的49倍。 c. 主语+谓语+倍数(分数)+ 形容词(副词)比较级+ than… The grain output is 8 percent higher this year than that of last year. 今年比去年粮食产量增加8%。 d. 还可以用by+倍数，表示增加多少倍 The production of grain has been increased by four times this year. 今年粮食产量增加了4倍。 2.分数表示法 构成：基数词代表分子，序数词代表分母。分子大于1时，分子的序数词用单数，分母序数词用复数： 1/3 one-third ； 3/37 three and three-sevenths.
[命题趋向]
2. one代替前面提到的同类事物中的一个。该事物只能是可数名词,前面可以有冠词,也可以被this、that或形容词修饰,其后也可以有定语
-Why don't we have a little break?
-Didn't we just have________?
A. it B. that C. one D. this
it, one和that虽然都可以用来替代前面所提到的一个单数名词,以避免重复,但在具体用法上却有不同。简述如下：
1. it代替前面提到的同一事物,该事物既可以是可数名词也可以是不可数名词
The news that they failed their driving test discouraged him, ______?
A. did they B. didn't they C. did it D. didn't it
答案: D
It seems as if we should finish it tomorrow.
4. 注意强调句型与定语从句的区别
这类题目往往比较难做，应对的方法是：
1)先试着将it ,be, that/who去掉，若删除后的句子结构和句子意思仍然正确，则为强调句
2)强调句中的that/who仅仅是标志词，不作句子成分，但在定语从句中that可作主宾表语，who可作主语，所以解题时应从分析句子成分入手，若that或who不作句子成分，且删掉后原句仍然成立，则为强调句型的引导词，若在从句中作某一成分，则为定语从句
It was at 7 o'clock that he came here yesterday.( 强调句型)
It was 7 o'clock when he came here yesterday.(定语从句)
3. 在强调not … until结构时必须把not与until一起放到被强调的位置上
It was not until she took off her dark glasses that I realized she was my brother.
His salary rises from 20 dollars a week to 35 dollars a
week.
They
have three times as many cows as we do.