电力系统的暂态过程有三种：即（）过程、（）过程和机电暂态过程。
参考答案：波；电磁暂态
—Where’s her second son? I haven’t seen him for a long time.
—He _______ Maine looking for a place to work.
A．will go to
B．has gone to
C．had gone to
D．goes to
元代瓷器的发展集中在江西的（）。
