在普通水准测量中，测站检核的作用是什么？有哪几种方法？ 

普通圆柱蜗杆传动的组成及工作原理是什么？它有哪些特点？宜用于什么情况？

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.

简述螺旋溜槽选煤的工作原理。

催化加氢净化轻苯原理是（）。

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。

绘出行星锥齿轮差速器的结构简图，并说明其差速原理及传动特点。为什么普通圆锥齿轮差速器是“差速不差力”？为了提高工程机械构造的越野性能，应该采用什么样的差速器，并简述其工作原理。

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。