求解线性方程组的高斯主元消去法的条件为（　）。

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.

用列主元消去法解线性方程组

齐次线性方程组的基础解系为（　　）。[2011年真题]

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。

线性非齐次方程的解与其对应齐次方程的解之和是非齐次方程的解。

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。