对折的

1.Once it's popped open, your cootie catcher will look like Picture 10.

现在把东南西北这样，开上面的小正方形。

2.The shape of cross-section is an ellipse folded in half through one symmetry axis, and the axis keeps perpendicular with pinacoid-view.

断面形状为沿称轴的椭圆，此称轴始终垂直轴截面，其方向与平面图上的流道中线无关。