It is a matter of the utmost urgency to find out what has happened to these people.

当务之急是弄清楚这些人出了什么事。

《柯林斯英汉双解大词典》

We are bitterly upset at what has happened.

我们对发生的事感到极其难过。

《柯林斯英汉双解大词典》

All this has happened because you couldn't be bothered to give me the message.

就是因为你嫌麻烦没通知我，才出了这事。

《牛津词典》

He says this is a very huge increase compared to what has happened in the past.

VOA: special.2009.06.03

A lot has happened since the exuberant optimism of the political spirit that we see in a tract like Areopagitica.

弥尔顿在《论出版自由》中发表了极为乐观的政治思想之后,政治形势发生了很大变化。

耶鲁公开课 - 弥尔顿课程节选

Because what has happened is that a lot of parents have had kids at such a young age

因为很多父母生孩子的时候还太年轻，

重要的是家庭教育 - SpeakingMax英语口语达人

There's nothing that has happened in that country that has not borne his print.

NPR: Cuba (and Cuban Exiles) Ponder the Future

Certainly that is what the data suggests has happened over the last several decades.

FORBES: NFL And Wisconsin Polls Showing Support for Players And Governor Walker

It works but what has happened is that Apple have changed the way websites are approved.

FORBES: First There Was Apple's MapGate, Now Welcome ParentGate