膝盖应该是平面的。
中国人用重力仪来校正海平面的局部偏差。
The Chinese used a gravity meter to correct for local deviations in sea level.
在此之前，气候的变化导致了海平面的剧烈波动，恐龙因此灭绝。
Changes in climate before that period caused severe fluctuation in sea level, resulting in the extinction of the dinosaurs.
白垩纪以前的气候变化导致了海平面的剧烈波动，引发了恐龙的灭绝。
Changes in climate before the Cretaceous period caused severe fluctuation in sea level, resulting in the extinction of the dinosaurs.
由于地下水位不是平面的，而是随着地形起伏的，所以地下水和地表水一样受到重力的影响。
Because the surface of the water table is not flat but instead rises and falls with topography, groundwater is affected by gravity in the same fashion as surface water.
当浮动冰架破裂时，对海平面的影响很小；而与之不同的是，固定在基岩上的冰盖将会使海面炸毁。
Unlike floating ice shelves which have little impact on sea level when they break up, the ice sheet is anchored to bedrock will blow the sea surface.
它的范围包括海平面的极地地区、4500米高的干燥的亚热带地区以及3500-4500米高的潮湿的热带地区。
It ranges from sea level in the Polar Regions to 4,500 meters in the dry subtropics and 3,500-4,500 meters in the moist tropics.
理论优化表明，三个吡啶甲酸分子都具有平面的平衡构型。
Theoretical optimizations show that the equilibrium geometries of the three picolinic acid molecules are planar.
这些令人惊叹的宝石包括在上雕琢平面的钙铝榴石石榴石、紫水晶和粉色碧玺方块。
The stunning gemstones include faceted Hessonite Garnet, Sugilite and Pink Tourmaline cubes.
然后利用法向量得出切平面的方程。
And then get this equation for the plane using the normal vector.
这意味着直线是平行于平面的。
它其实是朝垂直于平面的方向。
Well, it's the direction that's perpendicular to this plane.
其实它是水平面的面积元素。
Well, it is just going to be the area element in a horizontal plane.
这就是这个平面的方程了。
那么如果我选择了任何位于切平面的向量。
也就是说直线，实际上是平行于平面的。
OK, so that's what would tell you that the line is actually parallel to the plane.
现在，垂直于同一个平面的，有两个方向。
Now, there's two different possible directions that are perpendicular to a plane.
这是定义切平面的方法。
这就是切平面的方程。
海平面的上升威胁到任何海岸线。
而更具威胁的是海平面的上升速度。
But the far greater threat is the rate at which the sea level is rising.
所以，我们要怎么找，垂直于这个平面的向量？
So, how do we find this vector that's perpendicular to the plane?
谁说地球是平面的这种说法是错误的？
你还可以设定三维的纹理，使用形状替换平面的图像。
You can also set up three-dimensional textures, using shapes instead of a flat image.
我们已经知道，如何根据系数找到这个平面的法向量。
And, we know how to find a normal vector to this plane just by looking at the coefficients.
他在大颗钻石上雕琢小平面的技巧是不同凡响的。
The skill with which he faceted the great diamond is remarkable.
这就是切平面的，或者说这个曲面的法向量。
OK, and that's going to be the normal vector to the surface or to the tangent plane.
另一潜在的重要难民来源是由于海平面的上升。
Another source of refugees, potentially a huge one, is rising seas.
镜面反射：光线从有光亮平面的对象反射回来。
Specular reflection: The light that reflects off objects with a shiny surface.
镜面反射：光线从有光亮平面的对象反射回来。
Specular reflection: The light that reflects off objects with a shiny surface.
应用推荐