高中英语语法 之 分数、小数、百分数 等讲解与练习

一、分数

1.分数：表示分数时，分子须用基数词，分母须用序数词，分子大于1，分母为复数。

e.g.one-fourth 四分之一 two-fifths 五分之二

2.分子和分母的数目较大时，两者都用基数词，之间用over/by/out of/in 连接。

e.g.Seven over/out of/in twenty of the students have passed the flight test.

3.带分数：“整数+ and +分数部分”。

e.g.Two and a quarter inches of rain fell over the weekend.

二、小数

小数：小数总是用阿拉伯数字表达。小数点后不论有多少位都不能用逗号分开，但小数点之前的数依然按照三位一个逗号的原则书写。

0.786432 120,372.428

注意：小数点前的数按普通基数词的读法读，小数点后的数每一位都要单独读。

15.503 读作fifteen point five zero three

三、百分数

百分数：百分数中的数目用阿拉伯数字，后接percent或百分号（%），在专业统计或表格中常用%代替percent，在句首时则用英语单词书写。

e.g.I have invested 40 percent of my income.

四、倍数

倍数：表示倍数时，一倍用once，两倍用twice/double，三倍以上用“基数词+ times”。 常用句型：

1.“倍数 + as many/much … as …”

e.g.This computer costs three times as much as that one.

2.“倍数 + the size of …”

e.g.Our playground is five times the size of theirs.

3.“倍数 + what从句”

e.g.The value of the house is double what it was.

4.“倍数 + 比较级 + than”

e.g.The room is twice larger than ours.

5.“比较级 + than … + by + 倍数/程度”

e.g.The line is longer than that one by twice.

五、四则运算：

1.加法：在口语中，小数目的加法常用and代表“+”，is 或 are 代表“=”；在正式的场合或较大数目的加法用plus代表“+”，equals或is 代表“=”。

e.g.7+4=11 Seven and four is/are eleven.

13+12=25 Thirteen plus twelve equals/is twenty-five.

2.减法：在口语中，小数目的减法用“Take away +减数+ from +被减数+ and you get +余数”或者“减数+ from +被减数+ leaves/is +余数”；在正式的场合或较大数目的减法用minus 代表“－”，equals 代表“=”。

e.g.12-5=7 Five from twelve leaves/is seven. /Take away five from twelve and you get seven.

21-7=14 Twenty-one minus seven equals fourteen.

3.乘法：在口语中，小数目的乘法的乘数用复数形式，用are 代表“=”；大数目的乘法用times代表“×”，is/makes 代表“=”。在正式的场合下用multiplied by 代表“×”，equals 代表“=”。

e.g.4×5=20 Four fives are twenty

36×23=828 twenty-six times thirty-eight is/makes nine hundred and eighty-eight.

4.除法：小数目的除法：用divided by 代表“÷”，equals 代表“=”。“被除数+ divided by +除数+ equals +商”；“除数+ into +被除数+ goes +商”

e.g.32÷4=8 Thirty-two divided by four equals eight.

跟踪练习

1._____of the trees in the garden are apple trees.

A.Two third B.Two thirds C.Second third D.Second thirds

2.The _____ paragraphs are very important.

A. one third B.first one C.first three D.one three

3. China's population is about_____of the world's population.

A.the quarter B. one-four C. a quarter D. one-fourths

4.At a rough estimate,Nigeria is _____Great Britain.

A. three times the size as B. the size three times of

C. three times as the size of D.three times the size of

5.What a table! I've never see such a thing before. It is_____it is long.

A. half not as wide as B. wide not as half as

C. not half as wide as D. as wide as not half

6. John is the tallest boy in the class,according to _____himself.

A.five foot eight as tall as B. as tall as five foot eight

C. as five foot eight tall as D. as tall five foot eight as

7. After the new technique was introduced, the factory produced _____tractors in1988 as the year before.

A.as twice many B.as many twice C.twice as many D.twice many as

8. This river is_____that one.

A.as three times long as B.the third time as

C.three times the length of D.three times longer

9. About_____of the workers in the steel workers are young people.

A.third fifths B.three fifths C.three fives D.three fifth

10.71% of the surface of the earth_____sea.

A.is B.are C.were D.has been

答案：BCCDC BCCBA