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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The process of forming a 3-D figure from a 2-D surface is called extrusion.

从 2-D 平面形成 3-D 图形的过程称作挤压。

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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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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

They'd balance a spoon-shaped piece of magnetic rock on any flat surface, and since it was magnetic, the handle would swivel to align itself with the Earth's magnetic poles.

FORBES: Magazine Article

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