如果你是老板，不要约会你的下属。

If you are the boss, DON't date your subordinates.

youdao

那么我想我们就不要约会了！

Then I guess we shouldn't be dating!

youdao

我们今晚不要约他出去。

Let's not invite him out with us tonight.

youdao

So, the point is whenever you have derivatives with something over dt, do not hesitate to cancel the dts This will be actually true as long as both quantities are vanishingly small.

关键在于,只要你推出的式子分母上有dt,不要犹豫,直接约掉,这个式子只在,两遍都是无穷小的情况下成立

耶鲁公开课 - 基础物理课程节选