有2对磁极的直流电机、单波绕组、则此电机的支路数应为（）

直流电机的主磁极是由主磁极铁芯和励磁绕组组成。

直流电机的主磁极是由（）和励磁绕组组成。

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.

复励直流电机的励磁绕组和电枢绕组是（）。

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。

励磁绕组与电枢绕组串联，用本身负载电流励磁的电磁式电机称（）电机。

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。

磁场继电器的作用是（）交流发电机的励磁电路，即发电机（）时，自动接通发电机的励磁电路，发动机（）后，又自动断开发电机的励磁电路。