Test sites: points, lines, planes and bodies Special topics: analysis: move points into lines, lines into planes, planes into bodies, and then get the answers. The pen tip slides quickly on the paper to write one word after another, which is interpreted by mathematical knowledge as the point moving into the line. So choose: A. Comments: This question mainly examines points, lines, surfaces and bodies, and correctly grasping the relationship between them is the key to solving the problem.