This is how it happened.

事情的经过是这样的。

《新英汉大辞典》

This might sound far-fetched, but the startling thing about this theory is how likely it is to happen – and to have happened already.

这听起来可能有些牵强，但是关于这个理论令人吃惊的事情是，这种情形发生的可能性有多大——以及已经发生的可能性有多大。

youdao

Ron Paul: Well now, what has happened is that the concerns of how it come about, it’s not because I knew about this.

罗恩·保罗：怎么说呢，现在发生的事情是人们知道了原因在哪里，不是因为我知道。

youdao

Two ways of measuring how this happened and what difference it made is to realize, to return to what I said earlier, that big state structures involve bureaucracies.

如果要弄懂贵族如何获利,以及贵族获利所引起的改变,我们必须意识到大国必须建立官僚机构,我在前面曾提到过这一点

耶鲁公开课 - 欧洲文明课程节选

So, this is an absolutely outstanding discovery, even though, if we think about it, what is the probability that this happened, how often did this happen?

0个alpha粒子，这绝对是一个，很了不起的发现，虽然我们仔细想想？

麻省理工公开课 - 化学原理课程节选

It doesn't say 'this is how it happened'.

BBC: New Scotland Yard sign

And if they're running to run our government, they need to come out with an honest answer and say this is what happened, this is how it happened, and this is what we're going to do to rectify it.

NPR: Listeners' Money Questions Answered

Moore says this is how it might have happened.

NPR: Origin of AIDS Linked to Colonial Practices in Africa