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.

什么是水力光滑管？

水力光滑管与水力粗糙管.

何谓水力光滑管？何谓完全湍流粗糙管？

什么是光滑管（）。

壁面光滑的管道一定是水力光滑管。（）

管壁光滑的管子一定是水力光滑管。（）

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。

山西大学改为国立后，工学院存在哪些系？（）

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。