【简答题】并励直流电动机,当电源反接时,其中Ia的方向 ,转速方向 。
【单选题】How does Nick feel at the end of the conversation?
A.
worried because he is running out of time.
B.
thankful because he has more information about Jackie Baker.
C.
angry because the receptionist won't let him see Jackie Baker.
【简答题】How does the author reply to the question?