照明用交流电的电压是220V,则它们的最大值是()。
A、220V
B、380V
C、311V
D、537V
参考答案:C
根据答句写问句。
1. A: ________________________________________________ ?
B: It's Monday today.
2. A: ________________________________________________ ?
B: It's Mar. 1st today.
3. A: ________________________________________________?
B: My birthday is in October.
4. A: ________________________________________________?
B: My favourite season is winter.
5. A: _________________________________________________ ?
B: I often go shopping on the weekend.
如图所示,轨道ABC光滑,弹簧固定在水平轨道的C处,物体从A点由静止下滑,沿BC运动并撞击弹簧,在弹簧被压缩的过程中, 能转化成 能。