英語語法關於倍數的使用方法

表示增加多少或減少多少用by。

The number of students in our university has increased by 20 percent over the previous year.

我們大學的學生數量比上一年增加了百分之二十。

The output of coal went up by four times.

煤炭產量增加了四倍。

The production has multiplied by five times.

產量增加了五倍。

The saled of washing machines have increased by a factor of nine.

洗衣機的銷售量增加了9倍。

The production was reduced by thirty percent.

生產減少了百分之三十。

The cost of air-conditioners has decreased by 50 percent.

空調的成本下降了50%。

表示增加到/至……或減少到/下降到/至……用介詞to。

The students in our university have increased to 12,000.

我們大學的.學生已增加到一萬二千。

The production was reduced to thirty percent.

生產減少到百分之三十。

注意區分下列句型：

increased by 30% 增加了30%

increased to 3,000 增加到3,000

increase 3 times/threefold 增加至三倍 或 增加了兩倍

increase by 3 times 增加了三倍

3 times as long as 為……的三倍長，或比……長二倍

3 times longer than 為……的四倍長，或比……長三倍

decrease by 30% 減少了30%

decrease to 30% 減少至30%