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问题128教学中遇到的问题:1一个不透明的正四面体物体被一束垂直于桌面上的平行光线照射,则此正四面体在桌面上的射影可能是下列图形中的(把你认为可能的图的序号都填上).①②③④2一个透明密闭的正方体容器中,恰好盛有该容器一半容积的水,任意转动这个正方体,则水面在容器中的
Question 128 Problems encountered in teaching: 1 An opaque, tetrahedral object is illuminated by a beam of parallel light perpendicular to the desktop. The projection of this tetrahedron on the desktop may be in the following graphic (taking what you think possible The serial number of the diagram is filled in.) 12342 A transparent sealed cube container just holds half the volume of water in the container. Turn the cube in any direction and the water is in the container.