已知突然扩大管道的管径之比d1/d2=0.5，则其相应的水流流速之比v1/v2=（）。

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.

变直径圆管，前段直径d1＝30mm，雷诺数为3000，后段直径变为d2＝60mm，则后段圆管中的雷诺数为（　　）。[2012年真题]

等直径圆管中的层流，其过流断面平均流速是圆管中最大流速的（）

变直径圆管流，细断面直径d1，粗断面直径d2=2d1，粗细断面雷诺数的关系是：（）

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。

摩擦是一门新兴学科，它涉及数学、力学、物理、化学、冶金学、石油学、化学工程等学科。

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。