Dinosaurs have been extinct for millions of years.

恐龙已经灭绝几了。

You can't be too careful these days.

还是小心驶得船啊。

450,000 years old, 4.5 million years old, 4.5 billion years old or 4.5 trillion years old?

45、450、45亿还是4.5亿前呢？

Cereal processing has a history of over 10,000 years.

谷物加工历史已有上。

At 25 million years is a really long time.

2500 是很长时间。

What happened about 250 million years ago?

两亿五千前发生了什么？

Modern humans arose in Africa about 200,000 years ago.

现代人类大约在20前出现在非洲。

It takes 10,000 years to wear away an inch of granite.

按一英尺花岗岩耐磨一计算。

In geologic time, a million years is recent history.

在地质学角，一前属于近代历史。

Simbakubwa was a member of an animal group that appeared 62 million years ago.

非洲巨狮是6200前一类物种。

This tusk is over 30,000 years old.

这只象牙已经有3历史了。

Collagen probably cannot last longer than that.

胶原蛋白可能不能存在超过一。

And then waiting for what felt like millions of years.

假装它等了几。

And they think that happened roughly 200,000 years ago.

他们认为那大概发生在20前。

About 10,000 years ago, this crater was created by nature itself.

大约一前，这个火山口自然形成。

The strip of land, known as the Isthmus of Panama, was formed about 3.5 million years ago.

巴拿马地峡形成于350前。

But what about 10,000 years in the future?

但未一后呢？

Dinosaurs died out about 65 million years ago.

大约6500前恐龙灭绝。

We have no idea what was happening 50,000 years ago.

我们并不知道5前发生了什么。

50,000 years ago, conditions were much harsher.

5 前，情况要恶劣得多。