What happened to them remains somewhat of a mystery.

他们到底出了什么事，到现在仍可以说是个谜。

《牛津词典》

A new study has found that most three-year-old children can remember a lot of what happened to them a year earlier, and these memories are still clear while they are 5 and 6, but by the time they are over 7, these memories become weaker rapidly.

一项新的研究发现，大多数三岁的孩子都能记得很多一年前发生在他们身上的事情，在他们5岁到6岁的时候，这些记忆仍然清晰，但当他们超过7岁时，这些记忆就会迅速变弱。

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Look at what happened to them.

看看它们怎么样了。

youdao

Many have never spoken of what happened to them during the war and most have never confessed to the crimes they committed.

VOA: standard.2010.06.07

We talk about equality t give other nations voice of what happened to them.

我们主张平等,却不让其他国家清楚自己的处境，but，we，don’

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But also, they're talking about their stories - what happened to them when they were displaced.

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Have other rich, powerful nations fallen into massive debt (and what happened to them)?

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Ever since the first dinosaur skeleton was discovered, the question rose: what happened to them all?

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