if you don't want to use that, you can also derive it as we did every time, it should intuitively make sense how we got there. But the exams are pretty short, so we don't want you doing that every time, so we'll save the 2 minutes and give you the equations directly, but it's still important to know how to use them.

吸收的和发射的，如果你不想用公式,你也可以每次都向我们这样推导它,很直观的就能得到结果，但考试时间很短，我们不希望你们每次都推导,所以我们会直告诉你，让你节省2分钟，但知道如何应用它十分重要。

麻省理工公开课 - 化学原理课程节选

If two arrows are equal, you cannot be longer in the x direction and correspondingly short in the y direction.

如果要使两个矢量相等,那么即使 x 分量长一些,y 分量相应地小一些也是不行的

耶鲁公开课 - 基础物理课程节选

So among your printout from Wednesday, if you have it, you have a file called math1.c. If you don't have this, the programs are short today, so it should be easy enough to follow along visually, but a PDF and the actual source code is available online for these things.

从你们周三打印出来的资料来看，如果你们手上有的话，你们会看到有个叫做的“math1，c“的文件，如果你们没有资料，那些程序还是比较短的，所以你们应该可以很轻松地,来看这些程序，但是那个PDF文件,和实际的源代码都可以到网上找到,相关的资料。

哈佛公开课 - 计算机科学课程节选