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 （）.

The（）may examine or re-examine the goods or take samples from them straightaway in the absence of the consignee or the consignor whenever it considers this necessary.

（）are liable to be stoten, pilfered or may damaged due to improper handing or stowage.

Banks have no liability for any delay or loss caused by postal or telex failure.

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。

影响浅海化学沉积的主要因素是什么？研究浅海化学沉积有何重要意义？