1、倍数、分数、小数 与百分数的表示法,倍数,A. 两倍表示法 a. twice表示两倍： Twice nine is eighteen. 二九十八 This box is twice as large as that one. 这个盒子是那个盒子的两个大。 This box is twice larger than that one. 这个盒子比那个盒子大一倍。,double表示两倍 The top-brand cigarettes are often sold at double the normal price here. 这里名牌香烟售价经常比正常价高一倍。,B. 三倍表示法,triple
2、 n. 三倍数 Eighteen is the triple of six. 十八是六的三倍triple a. 三倍的 a triple dose of medicine 三倍剂量的药triple v. 增至三倍，使成三倍 The farm tripled its profits last year. 农场去年利润增至三倍 His income tripled. 他的收入增至三倍。,C. 四倍表示法,a. quadruple n. 80 is the quadruple of 20. 80是20的四倍。 b. quadruple a. 四倍的 The firm has an annual pr
3、ofit quadruple that of ours. 他们公司年度利润是我们的四倍。 c. quadruple v.（使）成四倍 They quadrupled output to around 20 million tons 他们把产量增至2,000万吨左右，是原来的四倍,D. 多倍表示法,a. 表示倍数用fold onefold 仅含一个的，单一的 twofold a. & ad. 两倍的（地） threefold a. & ad.三倍的（地）,三以上的倍数类推，即fourfold, fivefold, hundredfold等，其用法同twofold。 例如：a twofold in
4、crease 两倍的增加 He repaid the money twofold. 他加倍偿还了那笔钱。 The value of the house has increased fourfold since 1939. 房价自1939年以来增加了4倍。,b. 表示三倍或三倍以上可以用基数词加 times,at ten times normal speed 以十倍于正常速度的速度 three times the size of 是的三倍大 three times as large as 比大两倍 Output of coal increased four times （或fourfold）.煤
5、产量增加了3倍。,注意：下列同义句的表达方式不同：,GDP (gross domestic product) was four times as great as that of last year. 国民生产总值是去年的4倍。 GDP (gross domestic product) was four times greater that of last year. 国民生产总值比去年增加了3倍。,分数,A. 分数的构成 表示分数时，分子须用基数词，分母用序数词。分子如是1以上，表示分母的序数词须用复数形式。如下表所示：1/3 a (one) third 2/3 two thirds 3/5
6、 three fifths,B. 特殊分数的读法,a. 读作a (one) half（不读作one second） b. 读作a (one) quarter 也可以读作a (one) fourth c. 百分数的读法 %读作per cent 5%读作five per cent 0.5%读作 (naught) point five per cent,d. 数学中可都用基数词读, 如： 12读作 one over two 23读作 two over three 注意：复杂的分数多用此读法，如： 17/286读作seventeen over two hundred (and) eighty-six。,e. 整数与分数之间须用and连接 读作 five and a half,thanks,
