So, that's cosine theta d theta. And, well, if you do things with substitution, which is the way I do them, then you should worry about /2 the bounds for theta which will be zero to pi over two.

所以dx=cos，θdθ，如果用变量替换法来做，接下来就要考虑θ的取值范围,它是从0取到π

youdao

Many a time we don't know what we should do, but we still don't do it when we knew what we should d...

很多时候我们都知道要做什么，但是知道了该怎么之后，我们仍然不去做。

youdao

Some of the things I said--you'd probably say, well I should have known that an insurance company would have to do that, but it isn't.

对于我说的一些东西，你可能会说，我早就知道,保险公司会如此操作，但事实并非如此。

耶鲁公开课 - 金融市场课程节选

Here is what I'd say you should do.

这就是我说的你们必须做的

耶鲁公开课 - 基础物理课程节选

Rather than arguing about whether, or how, we should do something, you'd rather just go out there and get it done.

WHITEHOUSE: President Obama at Points of Light Forum in Texas

"I'd have thought that in this age of transparency we should be urging them to do that, " he told MPs during questions to his department on 5 December 2011.

BBC: Tory MP calls for trade union register