1. It is locally convex in the sense that it has no loops and the curvature never changes sign. 它的局部是凸的，因为它没有环路，且曲率永远不会改变符号。
2. The hyperbolic surface, which has so-called negative curvature because its surface curves up and down at the same time, like a saddle. 双曲曲面，即通常所称的负曲率，因为它的表面同时向上和向下弯曲，就像一个马鞍。
3. Curvature of the surface prevents slump block from becoming completely detached. 表面的曲率防止滑塌块完全脱离。
4. If the universe has a positive curvature, it's a closed universe. 正曲率的宇宙是封闭的宇宙。
5. It goes back... Actually, some of you may be able to see the curvature. 它回来了。，事实上，你们有些人，也许能看到曲率。
