简述布尔算符（OR）的作用。

肺炎临床以（）、咳嗽、气促、呼吸困难、肺部固定湿罗音为主要表现。

呼吸困难根据临床表现可分为（）、（）、（）。

呼吸困难分为吸气性呼吸困难、呼气性呼吸困难、混合性呼吸困难，请问以下哪项属于呼气性呼吸困难？（）

呼吸困难根据临床特点分为吸气性呼吸困难、呼气性呼吸困难和( )。

Every deliberate act of wrongdoing by the master or any of the crew against the ship or cargo，without the authorization or privity of the Shipowner or his agent，is（）.

（）, 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.

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。