观察图中神经刺激器，请问有关神经刺激器的描述，哪项错误（）

A.是一个脉冲发生器

B.产生刺激的波形为正弦波

C.频率都相同

D.可产生不同的刺激方式

E.用于机体不同部位神经的刺激

You are standing the wheelwatch on entering port and the master gives you a rudder command which conflicts with a rudder command from the pilot.What should you do?（）

A.obey the master‟s

B.obey the pilot‟s

C.bring the rudder to a position midway between the two conflicting orders

D.ask the pilot if he relinquishes control