| 摘要 |
<p>The system has a lid (3) comprising inner and external timber frames (9, 7) and a support base (18) that is made of timber, metal or plastics. Metal bars (17) are secured on the support base. A lid is provided at a terminal point of an aperture with a bonding agent (12). An end of a metal rod is fixed in the inner timber frame of the lid. A terminal lead i.e. wooden panel, is attached on a side of an inner surface of the support base, and serves to stabilize the lid if the lid is in an exact position.</p> |
