The left and right crotch seams of the skirt are more clear, and the back crotch seam is warped, so the straight crotch is shallow, and the width of the hole is moderate.

The trouser legs of the skirt trousers are A shaped, and the overlap of the left and right crotch joints can be seen. Only when crossing the steps can we see that the two trouser legs are separated, so the width of the door is wider and the crotch is deeper.

Because the total wave is bigger than the basic trousers, the back crotch seam does not become warped.

If the straight crotch is similar to the western trousers and the width of the trousers hole is less than 18 centimeters, then the way of the back crotch seam is similar to that of the western trousers, so that it should be warped properly.