在 + 过去 + Time Duration + 内
The word 过去 (guòqù) can function as a noun meaning 'the past' or a time phrase meaning 'in the past.' When used before a time duration, as in 在过去三周内, it means 'within the past three weeks.' It frames the action as having occurred during a defined earlier period.
在过去两年里,这座城市变化很大。
Zài guòqù liǎng nián lǐ, zhè zuò chéngshì biànhuà hěn dà.
In the past two years, this city has changed a lot.
过去的事情就不要再想了。
Guòqù de shìqíng jiù bùyào zài xiǎng le.
Don't think about things that have already passed.
在过去三个月内,公司的业绩有了明显提高。
Zài guòqù sān gè yuè nèi, gōngsī de yèjì yǒu le míngxiǎn tígāo.
In the past three months, the company's performance has improved significantly.