As its name implies, a face object represents a 2-d surface.

顾名思义，Face对象表示一个2 - D平面。

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The second part of a spatial reference system is its projection, which defines how to lay out the Earth surface onto a 2-d surface.

空间引用系统的第二部分是投影，它定义了如何将地球表面放置在2 - d平面上。

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Continual multi-point forming is novel technology for sheet metal 3-d surface forming.

连续多点成形是一种新颖的板材三维曲面成形技术。

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So if we want to talk about the volume of that, we just talk about the surface area, which is 4 pi r squared, and we multiply that by the thickness d r.

如果我们要讨论它的体积，我们要用的是表面面积，也就是４πｒ的平方，乘以厚度ｄｒ

麻省理工公开课 - 化学原理课程节选

So, they developed this bifurcated tool, which would be appl--you'd put the stuff on the surface of the tool and then you'd scratch the skin in a certain way so that you could produce sort of a reproducible introduction of the vaccine into the skin.

所以他们发明了一种分为两叉的工具,把疫苗抹在这种工具表面上,然后以某种方式在皮肤上刮,这样就能将疫苗,重复不断地引入到皮下

耶鲁公开课 - 生物医学工程探索课程节选

But the profusion of ultra-specific real estate blogs that followed in Steele's wake show he'd only scratched the surface.

FORBES: Real Estate Feature

The room erupted and the world learned we'd just made it to the surface of Mars.

BBC: Space - the new rock and roll

Scratch the surface, and you'd get the real story: 'I'm a lawyer, but I've always wanted to be X' -- invariably, it was some passion left over from childhood.

CNN: Try out 'dream job' before you jump