A convenient pant is characterized in that a run-through opening is arranged from acrotch to a front and back waist and the opening is provided with a slide fastener so as to close the opening.
一种方便裤，其特征在于：由裤裆至前后腰部设有贯通的可以敞开的开口，在开口上设有可将开口闭合的拉链。
2
There's a hole in the crotch.
裤裆上有个洞。
《牛津词典》
3
It will never be entirely flat because of the shape of the crotch seam, so I designed a bag with an elastic opening at the top so it wouldn't be a problem.