为什么需求价格弹性一般为负数。

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（）.

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

什么是需求价格弹性？怎样计算需求价格弹性系数？如何运用需求价格弹性系数来指导产品定价或调价？

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。

Demand curve（or demand schedule） 需求曲线（或需求表）

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。