转子灭磁能量的单位是（）。
A、A
B、V
C、W
D、J
参考答案：D
Robert is said ___________ abroad, but I don’t know what country he studied in .
A．to have studied
B．to be studying
C．to study
D．to have been studying
如何提高聆听和接收信息的技巧？
