But space isn't the only frontier.

但是探索太空并不是唯一的用途。

It's called the production possibilities frontier, or PPF.

它叫做生产可能性边界（PPF）。

You know, we recently crossed the final frontier.

我们最近还跨越了最一道防线。

Change cannot be held back by frontiers.

疆土边境不可能阻止变革。

And it's largely an unexplored frontier.

而且那里本上是一个未开发的领域。

It had closed the frontier a year ago for what it said were security reasons.

一年前，委内于安全原因关闭了边界。

It means expanding the frontiers of knowledge, your own, and then the world.

它意味着拓展你自己知识的前沿，然充到全世界。

Back in the early 1700s, though, western Pennsylvania was the distant frontier.

然而，在18世纪早期，西宾夕法尼亚就是遥远的边疆了。

Africa could really be the next frontier for technology growth, he said.

非洲有可能真的是下一个技术增长的前沿。他说道。

But antislavery forces in the North want to keep the frontier free.

而北方的废奴势力则要维护边远地区的自由。

I would say that America is probably the last frontier for Indian cuisine.

我会说美国可能是印度美食的最疆域。

Poland accuses Belarus of illegally pushing migrants into the block's eastern frontier.

波兰指责白俄罗斯非法将移民引导至欧盟东部边境。

Ten minutes later they were crossing the frontier that separated civilization from savagery.

几分钟之已经跨过了文明与野蛮的边界。

He said Ukrainians would defend their country if the Russians crossed the frontier.

他说，如果俄罗斯人越过边境，乌克兰人将保卫自己的国家。

It takes hours of diving to hit bottom, and it's largely an unexplored frontier.

要潜到水底需要几个小时，而且那里本上是一个未开发的领域。

We get that next frontier and create an experience that is second to none.

我们行走在领域前沿上，并创造着绝佳的体验。

So it's a European frontier. It's not just those of individual countries.

这是欧洲的边界。不仅仅是单个国家要承担的问题。

Humans tried to extend the frontiers of their territory, but they knew their limits.

他们很想张领土，但明白自身局限。

Through their great determination and incredible spirit, they pioneered the West and settled the frontier.

在她们伟大的决心和强大的精神支撑下，母亲们开拓了西部，并在边境定居。

Now that's the production possibilities frontier.

这就是生产可能性边界。