力系的主矢和主矩都与简化中心的位置有关（）。

平面一般力系平衡的充分必要条件是力系的主矢和主矩同时为零。

关于平面力系的主矢与主矩,下列的表述中不正确的是( )

关于平面力系的主矢和主矩,以下表述中错误的是( )。

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。

平面一般力系平衡的必要和充分条件是：力系的主矢和力系对任一点的主矩