Used to share the pressure, remember that the pressure at the bottom of the narrow container is smaller, and the tubing uses a similar inclined plane to transmit the outward pressure upward, thus reducing the pressure at the bottom.

In addition, the same principle is also used to precipitate impurities mixed with oil into red wine bottles (note that the bottom of red wine bottles is convex).

The dead zone looks like a dead corner, which means nothing is too big.