It is a soft cloth bag, usually in the shape of a round tube.

它是一种柔软的布袋，通常呈圆筒状。

It's usually made of cloth and it is hung on a large bar or large round tube that is on the top of the window.

它通常由布制成，挂在窗户顶部的大杆或大圆管上。

It's basically a small, round tube that connects to your engine and helps your car get rid of the pollution that is produced by the engine.

它基本上是一个连接发动机的小圆管，可帮助您的汽车清除发动机产生的污染物。