如右图所示，一束粒子（不计重力，初速度可忽略）缓慢通过小孔O₁进入极板间电压为U的水平加速电场区域I，再通过小孔O₂射入相互正交的恒定匀强电场、磁场区域Ⅱ，其中磁场的方向如图所示，收集室的小孔O₃与O₁、O₂在同一条水平线上。则                                                                 （    ）

在1－20各数中:

能被2整除的数有:____、____、____、____、____、____、____、____、____、____，这些数也叫____数.

不能被2整除的数有:____、____、____、____、____、____、____、____、____、____，这些数也叫____数．

(从小到大依次填写)

下列词语中加点的字，读音全都正确的一组是(   )

下列典故中，从物质变化的角度分析，主要体现化学变化的是（   ）

阅读短文，下列问题

      A boy goes to the cinema. He buys a ticket and goes in. But after two or three minutes he comes out. He buys a second ticket and goes in again. After a few minutes he comes out again and buys a third ticket. Two or three minutes after that he comes out the fourth time and asks for another ticket. The girl says to him, “Why are you buying all these? Are you meeting friends in the cinema all the time?”

     “No, I'm not doing that,” the boy says. “But a big woman always stops me at the door and tears(撕掉) my tickets.”