交流电动机的主要优点是结构简单和供电方便。一般采用（）交流感应电动机。
参考答案：三相
It is helpful for children to form a good habit by asking them to _____ all the toys after they finish playing.
A．put off
B．put down
C．put away
D．put out
CO中毒机制最主要是()
A．交感神经过度兴奋
B．迷走神经过度兴奋
C．COHb蓄积
D．高铁血红蛋白蓄积
E．抑制胆碱酯酶
