一个质量为m的物体，从倾角为θ，高为h的斜面上端A点，由静止开始下滑，到B点时的速度为v，然后又在水平面上滑行s位移后停止在C点，求：
① How many books do you have?____ A. I bought a lot of books.
② What are the rabbits doing?____ B. They are onions.
③ Can you play the piano? ____ C. I have twenty books.
④ What did you do last Sunday? ____ D. They are jumping.
⑤ What are these?____ E. Yes, I can.
在探究原子结构的过程中科学家提出了多种猜想，进行了多次实验并提出了不同的模型．如图中a所示的模型最早是由____提出的；b所示模型的中间黑色部分是____ ，它是根据c所示的实验结果提出的，该实验的名称是____ ．
