一、在一次测试中,要求画出以图1为三视图的几何体的直观图.小明成功做出了直观图(图2).测试之后,小明仔细端详三视图和它的直观图,看看能画出几种形状的截面;又联想以往研究过的图形,突发奇想:如果这个七面体是个实体,它是不是可以充当一些异形瓶口的塞子呢?沿着小明的思路,试回答下面的问题: First, in a test, asked to draw a three-dimensional view of the geometry of Figure 1. Xiao Ming successfully made a visual map (Figure 2) After the test, Xiaoming detailed three-dimensional view and its visual map to see Can draw several shapes of cross-section; Also think of previously studied graphics, whim: If the seven-sided body is an entity, it is not able to act as a stopper of the shaped bottle it? Along Xiaomin's train of thought, try to answer the following The problem: