It happened some twenty years ago.

这事发生在大约二十年前。

youdao

Some twenty years ago by merging two small-sized ones.

大约20年前由两个小规模的工厂合并而成的。

youdao

Some twenty years ago, social entrepreneurs were working alone, fundamentally they had no idea many times that other social entrepreneur existed.

在大约二十年前，社会企业家都孤军奋战，他们常常根本不知道有其他社会企业家存在。

youdao

And some people work at jobs that did not exist even twenty years ago.

VOA: special.2010.03.25

But while there and attired with some Charlotte insignia from nearly twenty years ago, I bonded with the 25-30 49er supporters who had made the trip from Charlotte.

FORBES: Charlotte 49ers Run To Final Four a Reminder of Positives Inherent in College Athletics

Twenty-five years ago, some footprints were found in Laetoli, Tanzania.

BBC: NEWS | Science/Nature | Robotics show Lucy walked upright

Twenty years ago, Dr Ericsson tried to prove it by training some ordinary laboratory volunteers up to prodigy-level performance in a number-memory task.

ECONOMIST: Who wants to be a genius?