The oldest of these, as far as we know, was the Indo-European family of languages, which were beginning to be spoken clear back during the Stone Age.

据我们所知，其中最古老的语言是印欧语系。 远在石器时代人们就开始使用印欧语了。

youdao

The scar on my hand was so clear that it brought me back to my childhood.

我手上的伤疤是如此清晰，以致让我想起了我的童年。

youdao

It is not clear how many of them will be heading back to Saudi Arabia tomorrow.

尚不清楚他们当中有多少人明天将折回沙特阿拉伯。

《柯林斯英汉双解大词典》

Today,VOA broadcasts to satellites in space that send the signal back to stations on the ground that transmit programs with a clear signal.

VOA: special.2010.12.08

I think if we look back, five years from now, it won't be nearly as clear how you separate what those products are.

回顾五年前，这些产品的区分,不像这么明显。

斯坦福公开课 - 戴尔CEO-Michael.Dell谈创业和发展课程节选

You denature them, you can watch them denature because the egg white turns from clear to white and it doesn't go back.

它们变性了,这种变性是可以观察到的,蛋清由透明变为白色,再也变不回去

耶鲁公开课 - 生物医学工程探索课程节选

Everyone -- a lot of people, and certainly we made clear back in December that a political effort to short-circuit that process for ideological reasons would be counterproductive because a proper review that weighed all the important issues in this case could not be achieved in 60 days -- according to the State Department, which, again, runs this review process.

WHITEHOUSE: Press Briefing

And Jones will be able to get clear title back to his property by paying the back taxes.

FORBES: Magazine Article

From now on, it's quite clear the back door will be firmly locked.

CNN: British politicians rightly close the door to Murdoch