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fourfold + noun
fourfold 作形容词时置于名词前，表示‘四倍的’。
The company reported a fourfold increase in profits.
该公司报告利润增长了四倍。
四倍；四重
先理解核心含义，再看它在真实句子里的用法。
四倍；四重
by a factor of four
The company reported a fourfold increase in profits.
该公司报告利润增长了四倍。
以四倍的方式。
By a factor of four.
The number of students at the school has increased fourfold in the past decade.
这所学校的学生数量在过去十年里增至四倍。
If you double the side length of a square, its area increases fourfold.
如果你把正方形的边长加倍，它的面积会增至四倍。
Our budget for the project has grown fourfold after the company expanded.
公司扩张后，我们项目的预算已增至四倍。
fourfold 作形容词时置于名词前，表示‘四倍的’。
The company reported a fourfold increase in profits.
该公司报告利润增长了四倍。
fourfold 作副词时修饰动词，表示‘以四倍的程度’。
The population increased fourfold over the century.
一个世纪内人口增加了四倍。
Not this
Sales increased fourfold times this year.
Use this
Sales increased fourfold this year.
fourfold 本身就表示“四倍/成四倍”，相当于 by a factor of four；再加 times 为多余。中文说“增长了四倍”，但英语里 fourfold 已包含“倍”的含义，不能写成 fourfold times。
Not this
The number of students grew fourfoldly over five years.
Use this
The number of students grew fourfold over five years.
fourfold 本身就可作副词，直接修饰动词 grow，表示“成四倍地”；不能按照一般副词规则再加 -ly。fourfoldly 是不存在的形式。
Focus on the distinctions below. Other candidates are kept compact until a reliable usage note is available.
四倍的增长
The company reported a fourfold increase in profits.
该公司报告的利润增长了四倍。
增加四倍
The population increased fourfold in the past century.
在过去一个世纪里，人口增加了四倍。
四倍的激增
There has been a fourfold jump in online orders.
网上订单出现了四倍的激增。
高出四倍
The cost is fourfold higher in the city center.
市中心的费用高出四倍。
他必四倍赔偿那只羊羔，因为他做了这事，又因他没有怜悯之心。
When King David heard Nathan's parable, he declared angrily that the rich man must restore the poor man's lamb fourfold.
大卫王听拿单的比喻后愤怒地宣告，那富户必须按四倍赔偿穷人的羊羔。
我若讹诈了谁，就还他四倍。
In the Gospel of Luke, Zacchaeus promises to repay anyone he has cheated fourfold.
在路加福音中，撒该承诺，凡是他讹诈过的人，他都要偿还四倍。
Use fourfold naturally, then get feedback on meaning, tone, grammar, and phrasing.
Revisit a common error or keep this word in your review list.
把纸对折(fold)四次，层数变成四倍：four(four)+fold(折叠)=四倍、四重。
语域：formal 常见场景：学术写作、正式报告、新闻语体 fourfold 表示“四倍/四重”，比较常见于正式书面语，如学术写作、正式报告或新闻语体；日常口语中则通常更常说 four times。
多与数量、程度等变化搭配；作形容词时可用作定语或表语，作副词时常置于动词后。
Dictionary facts from ECDICT, WIKTIONARY.