电力电子技术包括电力电子器件，变流电路和（）。

牵引变流器采用四象限脉冲整流器可以使电网侧的功率因数接近1。

第一和第二反抗期的共同特点是 (  ) 

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（）.

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。

可在第一和第四象限工作的变流电路是（）。

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。