什么是软化学合成方法？

请简要说明什么是软切换？

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 （）.

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。

某大学的一个学生必须参加下列六门课程中四门的考试：英语、历史、数学、生物学、化学、物理学。该学生必须应试生物学或者化学，但不能两门都考，数学和物理学两门课程中只能考一门。那么这个学生一定要考（ ）。

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。