So, in fact, this is called choosing an orientation of a surface.

事实上，这就是所谓的确定曲面定向的过程。

youdao

And the way it will work is that you have to choose an orientation of a surface, which just means choosing one of the two possible unit normal vectors.

具体方法是，先给曲面定向，也就是选择两个单位法向量中的一个。

youdao

Now, if a problem gives you neither the orientation of a curve nor that of the surface then it's up to you to make them up.

现在有一个问题，就是既没有给曲线也没有给平面定向，那要有你们自己去决定。

youdao

We're not going to front like we understand exactly how it works, but two IBM researchers in California have announced that they've gotten closer to controlling the orientation and magnetic spin of individual iron atoms on a copper surface, which would have huge implications for nanotech storage -- imagine the basic tech in your hard drive shrunk down the molecular level.

ENGADGET: IBM researchers get closer to nanotech hard drives