我国的电力系统中，国家规定动力和照明用电的频率为50赫兹，习惯上称为工频，其周期为（）
A.50S
B.0.04S
C.1S
D.0.02S
参考答案：D
Deeply _____ by the hero’s deeds, he decided to do something for the people.
A．moving
B．moved
C．being moved
D．having moved
什么是“三反”运动？
