Answer:First, second and last.
Explanation:
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Cross sections perpendicular to the base and through the vertex will be triangles. Below, you can see a plane cutting through the pyramid, part of the pyramid removed, and the cross section. You could also take a slice parallel to the base. Cross sections parallel to the base will be hexagons.
There are many people in urban areas. If there are floods, it could kill a lot of people. Also, floods sometimes damage buildings. If the buildings collapse, it would cause a big problem.