| 摘要 |
<p>The cover is in the form of a tunnel made up of a number of modular archways coupled end to end. Each archway comprises two half arches joined at the ridge by a hinge which can be locked by the insertion of pins. Each half arch has a metal frame sandwiched between inner and outer sheets of aluminium or galvanised steel. Thermal insulating material pref. expanded polyurethane, is packed between the sheets.</p> |
