| 摘要 |
On the underside of the main sheet (10) of the trampoline is fixed another sheet (26) which is permeable to water. It is of a colour contrasting with that of the upper sheet, so that any tears in the latter may be discerned. The under sheet is fixed to the outer doubly folded parts of the upper sheet and can absorb loads occurring in the event of damage to the upper sheet. |
