分数词

1）分数词构成法：
分数词（Fractional Numerals）由基数词和序数词构成，基数词代表分子，序数词代表分母。除了分子为1的情况下，序数词都要用复数形式：
1/4  one-fourth                 5/9  five-ninths
2/3  two-thirds                 3又2/5  three and two-fifths
7/12 sven-twelfths              47又3/8 forty-seven and three-eighths
此外还有下面表示法：
1/2  a (one) half                1/4  a (one) quarter
3/4  three-quarters              2又1/4 two and a quarter
1 1/2 one and a half             7又3/4 seven and three quarters
比较复杂的分数读法如下：
23/9 twenty-three over nine        76/92 seventy-six over ninety-two
2）分数在句中的作用：
分数在句中可用作：
a. 主语：
A quarter of the population voted for him. 四分之一的人投他的票。
The other third of the black population live in poverty. 另外三分之一的黑人生活在贫困之中。
Three-fifths of the computers on display were home-made. 展出的电脑五分之三是国内生产的。
b. 宾语或介词宾语：
Mother divided the cake into thirds. 妈妈把蛋糕分成三份。
Give a quarter of the pie to each of them. 给他们每人四分之一块馅饼。
They account for one-seventh of the population. 他们占人口的七分之一。
c. 表语或同位语：
The crop that year was only one-third of the usual amount. 那年的收成只是常年产量的三分之一。
Over twelve million people, about three-fifths of the local population are Hans. 有一千二百多万是汉人，约占当地人口的五分之三。
d. 定语：
It’s one-twentieth the thickness of a human hair. 它相当于人的头发丝二十分之一那么细。
The mass of an electron is 1/1850 that of a hydrogen atom. 电子的质量只是氢原子质量的1/1850。
It produces power at 1/8 the cost in a thermal power plant. 它的发电成本只是热电厂成本的八分之一。
e. 状语：
China is one-sixth larger than the United States. 中国比美国大六分之一。
This substance reacts one-tenth as fast as the other one. 这种物质的反应速度只是另一种物质的十分之一。

1） 小数的读法如下：
6.4——six point four
0.8——zero (或naught) point eight
0.05——(naught) point seven two six 或zero point seven two six
0.726——（naught）point seven two six或zero point seven two six
12.409——twelve point four oh nine
709.06——seven hundred and nine point oh six
2）小数主要用作定语：
Our grain output is now 2.4 times that of 1980. 我们现在的粮食产量是1980年的2.4倍。
Its total output value was up 4.7 times. 它的总产值提高了4.7倍。
Its capacity was 7.3 times as great as in 1985. 它的生产能力是1985年的7.3倍。

百分数由percent（美作percent）表示，可以在句中作：
1） 主语：
Over eighty percent of all families own a television. 百分之八十以上的家庭都有电视机。
What percent of the population can read? 人口中能识文断字的百分比是多少？
Ten percent of the pupils are absent today. 今天有百分之十的学生缺席。
2） 宾语或介词宾语：
They constitute eight percent of the population. 他们占人口的百分之八。
The price of bread has gone up by 40 percent in two years. 面包价格两年间涨了百分之四十。
The bank charges interest at 12 percent. 银行贷款利息为百分之十二。
3） 定语：
Leave the waitress a 15 percent tip. 给女招待留下百分之十五的小费。
There is a ten percent service charge. 要收百分之十的服务费（小费）。
I paid him four percent interest. 我付给他百分之四的利息。
4）状语：
I think it’s ninety percent probable. 我看这有百分之九十的可能。
I’m not a hundred percent convinced myself. 我自己也不是百分之百全信。
Prices have risen 6 percent in the past year. 过去一年里物价上涨了百分之六。
偶作表语：
12 is 1 percent of 1,200. 12是1,200的百分之一。