下面关于电力系统运行特点说法正确的是（）。
A.电能可以大量储存
B.暂态过程缓慢
C.发、用电实时平衡
D.电网频率不可以出现偏差
参考答案：C
My mother asked me where _____, and I told her that I was going to buy some food.
A．I am going
B．am I going
C．I was going
D．was I going
3，15，7，12，11，9，15，( )
A．6
B．8
C．18
D．19
