让我们告诉你什么服务的目的所在。

Let us show you what service is all about.

youdao

让我们告诉你如何做模型。

Let us show you how to make a model.

youdao

让我们告诉你更多！

Let us tell you more!

youdao

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