Lenses can be divided into concave lens and convex lens.

镜片可以分为凹镜和凸镜。

Special geological conditions make the city's roads concave.

特殊的地质条件使得这个城市的马路是凹陷的。

The flood covered the concave road, so be careful when walking.

洪水盖住了凹陷的路面，走路要小心。

He has a concave stomach.

他的胃是凹的

He has a concave stomach.

他的胃是凹的。

He had a concave chest.

他曾有一个凹陷的箱子。

The palm of one's hand is slightly concave.

人的手掌是微凹的。

Since this is a concave function, it's not just the expected value.

由于这是一个凹函数，它不仅仅是期望值。

Because there is no abrasion between the concave and convex, the nut is reusable.

由于凹面与凸面之间没有磨损，螺母可以重复使用。