In this case, we must know how to say no politely.

既然如此，我们就必须知道如何有礼貌地说不。

youdao

To know things well, we must know them in detail; but as that is almost endless, our knowledge is always superficial and imperfect.

为了充分认识事物，我们必须详细了解它们，然而那几乎是没有穷尽的，所以我们的知识总是肤浅和不完善的。

youdao

So, we must know what we mean by action;

因此我们必须知道什么是行动；

youdao

"You know my rule,Andy. In all illegal activities, we must obey the law, in every detail.

VOA: special.2010.04.24

And we must know what the result is supposed to be. Typically when you run an experiment, you say, and I think the answer will be x.

这样我们可以来查看代码的进程,我们还必须清楚结果应该是怎么样的，比如当你运行一个实验的时候。

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He says, "I believe in the practice and philosophy of what we have agreed to call magic, in what I must call the evocation of spirits, though I do not know what they are."

他说我相信我们所称作的,关于魔法的实践和哲学，我认为那是对灵魂的召唤，尽管我并不知道它们是什么“

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We must know and respect all the different cultures that we work for.

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We must know what the world needs first and then invest ourselves to supply that need, and success is almost certain.

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To do this, we must know who our students are and what their hopes and dreams are because if we cannot motivate them and inspire them, how do we expect to teach them?

WHITEHOUSE: I Love You Too Much to Let You Fail: A Path to Transformational Change | The White House