为了节约能源,小明响应政府号召,将家中的空调温度调高1℃,每小时可节约用电0.5kW•h,如果一天使用空调6h,则小明家中每月(以30天计),可以节约用电 ____ kW•h.每1kW•h能让功率为40W的电灯正常工作 ____h.
细线下挂一个质量为m的小球,现用一个力F拉小球使悬线偏离竖直方向θ角处于静止状态,如图所示,则拉力F的最小值为____,与竖立方向间夹角为____.
What happened?
____ hit an old man.
Where did the accident happen?
On ____
Who sent the man to the hospital?
____
Is the traffic busy now?
What's the suggestion of the reporter?
To go____.