I understood how it had happened.

我明白这是怎么回事。

youdao

Now it had happened.

现在它发生了。

youdao

I couldn't believe how quickly it had happened.

我真不敢相信这一切发生地这么快。

youdao

When Hank sang a sad song, those who listened knew it was about something that had happened to him.

VOA: special.2009.11.22

What is happened is that it is spread to Parkistan and we had a gradual eliminationof many Pashtun tribes.

而是这些组织蔓延到了巴基斯坦,还有就是普试图人在逐渐减少。

普林斯顿公开课 - 国际座谈会课程节选

I knew...when it happened, a lot of people had died.

我知道……它发生的时候，死了很多人。

911事件的影响 - SpeakingMax英语口语达人

It had happened only three times in her life, less than once a decade.

NEWYORKER: Shauntrelle

He claimed it had happened after Mr Aryaei Nekoo had threatened him with a knife.

BBC: Stephen Nolan

If it had happened, his home market would be better prepared for attacks from abroad.

ECONOMIST: Twin challenges to Italy to open its banking industry