People who have seen this before, done it before, lived through it, and now you can count on them not to run away, better than you can on a fresh recruit who's never done this before.

有经验,杀过人,亲历过战争的人,往往可以靠得住,不至于临阵脱逃,从没参加过战斗的新兵蛋子一般都不怎么靠谱

耶鲁公开课 - 古希腊历史简介课程节选

So we created this on-site service program for servicing PCs, which had never been done before.

所以在PC服务方面,我们开启了现场服务项目，这是史无前例的。

斯坦福公开课 - 戴尔CEO-Michael.Dell谈创业和发展课程节选

I've never done this sort of thing before."

我从来没有做过这事以前“

耶鲁公开课 - 死亡课程节选