（）, 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 （）.

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。

编写梯形图语言应该遵循哪些原则？

PLC常用的编程方式有梯形图编程和指令语句编程等。

在PLC梯形图编程语言中，下列说法不正确的是（）。

F1系列PLC—OR指令表示（）。

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。