double|doubled|doubles|doubling

政府目标是在25年内使高等教育学生人数翻倍。

The government aims to ___double the number of students in higher education within 25 years.

自引进新技术以来，公司利润已翻了一番。

Company profits have ___doubled since the introduction of new technology.

税收已经翻倍，而且汽油价格在过去3个月内上涨了50%以上。

Taxes have ___doubled, and the price for petrol shows an increase of more than 50% within the last 3 months.

由于移民，这座城市的人口每十年翻一番。

The population of the city ___doubles every decade due to migration.

这家公司今年正在加倍投资可再生能源。

The company is ___doubling its investment in renewable energy this year.