因为一直到现在我们都是在看图像，而且知道它们，是相切的，但是为什么在一般情况下它们都相切？
Because so far I have shown you pictures and have said see they are tangent.But why is it that they have to be tangent in general?
我们知道梯度向量垂直于这个向量，而速度向量是相切于等值面的，其他相切于等值面的向量，又如何呢？
We know that the gradient is perpendicular to this vector that's tangent to the level surface What about other vectors tangent to the level surface?
水是建造时间入口的屏障元素，该入口被用作在相切涡汇处的各个相切宇宙之间的门关。
Water is the barrier element for the construction of Time Portals used as gateways between Universes at the Tangent Vortex.
水是建造时间入口的屏障元素，该入口被用作在相切涡汇处的各个相切宇宙之间的门关。
Water is the barrier element for the construction of Time Portals used as gateways between Universes at the Tangent Vortex.
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