英语里increase by n times/increase n times用法都是可以的，在一般情况下，两者的含义是相同的，都表示：增加到n 倍，或增加了n-1倍。
His money increase (by) six times during that period.
在那段时间里，他的钱增加了5倍。
Foreign investments there increased （by）six times.
那里的外国投资增加了5倍。
The steel output has increased (by) two times.
钢产量已增加了一倍。
Growth has gone to the very, very top, whose share has almost increased four times since 1980.
增长已经达到了最高点,自1980年以来,其份额几乎增长到四倍。
六级真题- 2015年 6月 2卷 信息匹配
The output is twice as much as that of ten years ago.
产量是10年前的两倍。
New drivers have twice as many accidents as experienced drivers.
新驾驶员所出的事故是老驾驶员的两倍。
Britons are spending twice as much on health tonics as they were five years ago.
英国人如今在健康补药上花的钱是5年前的两倍。
Although he was twice as old as us, he became the life and soul of the company.
虽然他的年纪是我们的两倍，但他却成为了公司的灵魂人物。
He was arrested at his home in Southampton after a breath test showed he had drunk more than twice the legal limit for driving
呼吸测醉检测显示其饮酒量是法定驾车饮酒限量的两倍多，他随即在南安普顿的家中被捕。
Her original investment has increased twofold.
她原先的投资已经增加到两倍。
This figure means a twofold increase in production.
这一数字意味着生产提高了两倍。
Cases of food poisoning have trebled in the last two years.
在过去的两年里，食物中毒事件增加了两倍。
He trebled his earnings in two years. 他在两年间收入增加了两倍。
He trebled his earnings in two years. 他在两年间收入增加了两倍。
They will have to pay much more when rents treble in January
一月份房租增加两倍时，他们将被迫多付不少钱。
The city has trebled the number of its prisoners to 21,000.
该市的囚犯人数增长了两倍，达到21,000人。
The merger puts the firm in a position to triple its earnings.
合并可使公司利润增长两倍。
Capital expenditure was treble the 2002 level.
资本支出是2002年的三倍。
The amount of alcohol in his blood was triple the legal maximum.
他血液中的酒精含量为法定最高限量的三倍。
He was nearly three times over the drink drive limit. 他超过醉酒驾驶规定标准快三倍了。
The metal had been valued at twice or thrice its current price.
这种金属以前的估价是目前价格的两到三倍。
柯林斯高阶英汉双解学习词典
下面是有关倍数的考题：
BrightLine iTV, which designs and sells interactive ads, says interest has surged: it expects its revenues almost to triple this year.
设计和销售互动广告的Bright Line ITV认为该领域的利润已经初步浮现，它预计自己的收入本年将会增长到三倍。
六级真题- 2016年 6月 1卷 阅读A
The team at Stanford investigated the aquifers below this depth and found that reserves may be triple what was previously thought.
斯坦福大学的研究小组对这一深度以下的地下蓄水层进行了调查，发现蓄水量或许是先前所认为的三倍。
四级真题- 2018年 12月 1卷 阅读A
What's indisputable is that it's growing very quick Between now and 2050, the urban population of Africa could triple.
无可争议的是它在快速的增大，从现在到2050年，非洲的城镇人口会激增到目前的三倍。
四级真题- 2017年 12月 2卷 阅读A
The electronic waste stream is increasing three times faster than traditional garbage as a whole.
电子垃圾流的增长速度是所有传统垃圾的三倍。
高考真题- 2015 江苏 阅读B
Can you imagine a sea of sand three times bigger than India?
你能想象一片比印度大三倍的沙海吗?
