| 摘要 |
<p>A sloping surface (411) slopes downward. Longwise ribs (421) are provided to be adjacent to each other on the sloping surface. The longwise ribs extend from an upper area of the sloping surface to a lower area of the sloping surface. A diagonal rib (431) diagonally crosses a direction orthogonal to a direction of a gravitational force on the sloping surface. The diagonal rib is not taller than the longwise rib.</p> |
