“变成三倍”常见的英文表达有 “triple”（作动词）或 “become three times as large/much” 等。具体用法示例如下：
Triple：
The company's profits have tripled in the last year.（去年公司的利润变成了原来的三倍 。）
Become three times as large/much：
The population of this city has become three times as large as it was ten years ago.（这座城市的人口已经变成了十年前的三倍。 ）