如图所示，用“碰撞实验器”可以验证动量守恒定律，即研究两个小球在轨道水平部分碰撞前后的动量关系．

    Everyone wants to be successful. But failure is a common(普通的) thing for us to meet with.1, sometimes we fail the exams, sometimes in the sports meet, others 2but we fail. So 3everybody meets with the failure in his life.

    However, different people have different 4to deal with the failure. Some people lose

    hope when they fail. They seem to think that it is the5of the world. Others don't take failure 6. They seem to think that failure is the first step(步骤) to success. They will keep up and try their best  7the final success.

    Now let's imagine (猜想) the ends of the two ways. If we are afraid of the failure and always feel 8, and don't try our best to change ourselves, we may meet with more and more failures. But if we are hopeful and brave to face them, and never give up, we will 9 successful and our dreams will come true some day.

    So, please remember: Life doesn't give us the pleasure we want. But if we never give up and10do little by little, it will make a big difference.

北京周围的地理事物与实际不符的是