（）, or drum is used for hauling in or letting out the wires or ropes which will fasten the ship to the shore.

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 （）.

简述合同的成立必须具备的三个要件？

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。

假说的形成和发展通常包括三个步骤，这三个步骤依次是假说的提出、（）和假说的验证。

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。

简述假说成立的三个条件。

布尔逻辑具体检索时，是通过三个布尔运算符来实现其功能的：AND、OR、（）。