So, just to get you used to this idea, I'm going to draw a level surface of a function of three variables OK, so it's a surface given by the equation w of x, y, z equals some constant c.

为了令你们习惯于这个想法，我画一个三变量函数的等值面,这是一个平面,由函数w=c给出的。

youdao

The surface area of aggregate per unit volume of mortar does have influence on the mean value of the nearest surface spacing, but the ratio between them is not constant.

单位砂浆体积下集料的表面积的变化对邻近集料表面最近间距的平均值有影响，但二者之间的比值并非常数。

youdao

Based on this foundation, basic models of plow-bottom surface are ruled surface and negative constant curvature surface.

据此得出直纹和负常曲率两类曲面可作为犁体曲面的基本模型。

youdao

When you're falling to the surface of the Earth, you are describing a problem of constant acceleration.

当你讨论下落问题时,你在描述一个加速度恒定的问题

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