要想有一副好看的身材，你就必须要注重饮食！

If you want to have a beautiful body, you have to watch your diet!

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要提升，你就必须要放弃。

To go up, you have to give up.

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要购买食物或问路，你就必须与当地人交谈。

To buy food or ask directions, you have to start a conversation with local peoples.

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But once you start publishing things in between covers, you actually have to decide what goes in and what goes out.

但一旦你开始把书籍加上封面出版，你就必须决定要出版哪些书。

耶鲁公开课 - 新约课程节选

Or if you want negative numbers, between negative 2 billion and positive 2 billion, but it's a finite range.

或者你想储存一个负数，就必须位于负20亿到,正20亿之间，是个有限的范围。

哈佛公开课 - 计算机科学课程节选

What this has to do with global economy is that you have to be able to feed the population.

这与世界贸易之间的关系,就在于你必须先让民众衣食无忧

耶鲁公开课 - 欧洲文明课程节选