英语倍数增加或减少

　　在英语中表达倍数的增加或减少的方法有很多种。现将常用的英语倍数句型及其正确译法归纳如下：

　　一、倍数增加

　　(一)There is a n-fold increase/growth…(⑧) 应译为：增加n-倍(或增至n倍)。这个句型还有其它一些形式： Eg. A record high increase in value of four times was reported. 据报道,价值破记录地增长了3倍。

　　(二) A is n times as great(long，much，…)as B.(①) A is n times greater (longer， more，…)than B.(②) A is n times the size (length， amount，…)of B.(③) 以上三句都应译为;A的大小(长度，数量，……)是B的n倍[或A比B大(长，多，……)n-1倍]. Eg. This book is three times as long as (three times longer than，three times the length of )that one. 这本书的篇幅是那本书的3倍(即长两倍)。 注：当相比的对象B很明显时，than(as，of)B常被省去。

　　(三)double (增加1倍)，treble(增加2倍)，quadruple(增加3倍)。(⑨) Eg. The efficiency of the machines has been more than trebled or quadrupled. 这些机器的效率已提高了2倍或3倍多。

　　(四)increase to n times(④) increase n times/n-fold(⑤) increase by n times(⑥) increase by a factor of n(⑦) 以上四式均应译为：增加到n倍(或：增加n-1倍)。 Eg. The production of integrated circuits has been increased to three times as compared with last year. 集成电路的产量比去年增加了两倍。 Eg. The output of chemical fertilizer has been raised five times as against l986. 化肥产量比1986年增加了4倍。 Eg. That can increase metabolic rates by two or three times. 那可使代谢率提高到原来的2倍或3倍(即提高1倍或2倍)。 Eg. The drain voltage has been increased by a factor of four. 漏电压增加了3借(即增加到原来的4倍)。 注：在这类句型中increase常被raise，grow，go/step up，multiply等词所替代。

　　(五)此外，英语中还有一种用again而不用倍数词来比较倍数的方法，如： A is as much (large，long，…)again as B.(= A is twice as much (large，long，…)as B.(⑩) 应译为：A比B多(大，长，……)1倍。 A is half as much (large， 1ong，…)again as B. 【= A is one and a half times as much (large， 1ong，…)as B.】(11) 应译为:A比B多(大，长……)一半(即A是B的一倍半)。

　　二、倍数减少

　　(一)There is a n-fold decrease/reduction… 应译为：减至1/n [或：减少(n一1)/n]。(17) 这个句型还有其它一些形式， Eg. A rapid decrease by a factor of 7 was observed. 发现迅速减少到1/7。 Eg. The principal advantage of the products is a two-fold reduction in weight. 这些产品的主要优点是重量减轻了1/2。 从上列倍数增减句型及其译法中不难看出：与汉语不 同的是，英语在表述或比较倍数时，无论使用什么句 型(除了不含倍数词的again句型外)都包括基础倍 数在内，因此都不是净增或净减n倍，而是净增或 净减n-1倍。所以句型⑤、③表示的倍数增量=句型④; 句型(13)表示的倍数比差=句型12，且decrease(by) 3 times应译为“减少2/3，而不是“减少3/4。

　　(二)A is n times as small (light，slow，…)as B.(12) A is n times smaller (lighter， slower，…) than B.(13) 以上两句均应译为：A的大小(重量，速度，……)是B的1/n[或A比B小(轻，慢，……)(n-1)/n]。 Eg. The hydrogen atom is near1y l6 times as light as the oxygen atom. 氢原子的重量约为氧原子的1/16(即比氧原子约轻15/16)。 Eg. This sort of membrane is twice thinner than ordinary paper. 这种薄膜比普通纸张要薄一半(即是普通纸厚度的1/2)。 注：当相比的对象B很明显时，than/as B常被省去。

　　(三)decrease n times/n--fold (14) decrease by n times(15) decrease by a factor of n(16) 以上三式均译为：减少到1/n[或：减少(n-1)/n]。 decrease常被reduce， shorten， go/slow down等词替代。 Eg. Switching time of the new-type transistor is shortened 3 times. 新型晶体管的开关时间缩短了1/3(即缩短到2/3)。 Eg. When the voltage is stepped up by ten times， the strength of the current is stepped down by ten times. 电压升高9倍，电流强度便降低9/10(即90%)。Eg. The equipment reduced the error probability by a factor of 5. 该设备误差概率降低了4/5。