No matter what happens now, it's already done. Global growth will be deeply negative.

VOA: standard.2009.04.16

One is the processing has already been done so the introns are already out, so you don't have to figure out what's exon and what's the intron, it's already done for you.

一是DNA已经过处理,内含子已经没有了,你不用分辨哪些是外显子哪些是内含子,这些都已经帮你做好了

耶鲁公开课 - 生物医学工程探索课程节选

The idea of turning waste water into drinking water may see repulsive to some, but experts say it's already being done elsewhere on a smaller scale.

CNN: San Diego hopes to recycle waste water

Then they said, 'It's already been done.

WSJ: He Drills for Answers | Robert M. Edsel | Cultural Conversation by Joanne Kaufman

If it's hot somebody has already done it.

WSJ: How Did Those 'Ugly Dolls' Come to Be? Their Creators Explain