| 摘要 |
The construction has multiple intermediate steps (7-23) surrounding a common axis (41) and supported by a mutual support. A rear long edge, and inner and outer edges are located near a common center line. A common cover covers an imaginary center line circumference surface. A peripheral edge forms a projection on a base (25). A front edge of a top step (5) stretches parallel from a peripheral edge part. The common axis inclines in a vertical plane common imaginary axis. An imaginary plane extends near an inner end edge of the top step to another peripheral edge part (31). |
