如果你用绳子拴住一个小球使它在光滑的水平面上做圆周运动,当绳子突然断裂后,小球将( )
A:保持原来的圆周运动
B:保持断绳时的速度做匀速直线运动
C:小球运动速度减小,但保持直线
D:以上三种情况都有可能
俗话说:“塞翁失马,焉知非福。”从所学知识看,最早指出类似观点的是( )
cook, on, do, live, busy, read, play, about, clean, weekend
Hello! My name is Zhang Ming. I ____ in Qingdao. I am a student. Do you want to know about my ____? I'm very happy ____the weekend. I can ____many things(事情). Usually I do my homework and ____books. Sometimes I ____the rooms and ____dinner with my mum. I often watch TV and ____ pingpong with my father. I'm ____at home. This is my weekend. What ____your weekend?
我国共有____个省级行政单位.