A salvor may be（）the whole or part of the payment due under Salvage Convention to the extent that the salvage operations have become necessary or more difficult because of fault or neglect on his part or if the salvor has been guilty of fraud or other dishonest conduct.

The （） is used for hauling in or letting out the wires or ropes.

Vessels must be（）valid certificate of nationality or certificated of registry or license.

When loading or discharging dry mud or cement，crew members should use goggles and（）.

Effects which are dutiable or subject to prohibitions or restrictions should be declared in （）.

（）耐火等级建筑构件，除防火墙体外其余构件可采用难燃烧体或燃烧体。

（）耐火等级建筑的主要构件，除防火墙体外，其余构件可采用难燃烧体或可燃烧体。

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。

以下建筑构件属于难燃烧体的是（）

难燃烧体是指用难燃材料做成的建筑构件或用难燃材料做保护层的建筑构件。

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。

建筑构件允许采用难燃烧材料（难燃烧体），但耐火极限不应低于（）。