Of if is concave up on one side of and concave down on the other side.

点，如果在点的一侧是凹的，而在的另一侧是凸的。

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The studio estimates its Concave Roof system could help the school collect up to 28 cubic metres of rainwater, which would contribute to its running.

工作室估计该凹屋顶系统可以为学校收集高达28立方米的雨水，这将有助于学校的运行。

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Firstly, a telescope system is made up with a concave lens and a long-focus convex lens, by which the angle of the parallel beam from the collimator can be change.

该方法借助一个焦距较长的凸透镜与被测凹透镜组成无焦系统，可以使准直管出射光束的张角发生改变；

youdao

Mr Giles's solution to the drag problem is a sharp bow that cuts through waves up to 40 feet high, and a concave hull bottom.

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