自然科学的四大门类即基础科学、农业科学、工程科学和医学科学。

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.

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

疯牛病与人类克雅病的病原称（）。

疯牛病与人类克雅病的病原称

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。

疯牛病的病毒被认为是一种：（）。

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。