题干

2009年2月11日,俄罗斯的“宇宙-2251”卫星和美国的“铱-33”卫星在西伯利亚上空约805 km处发生碰撞.这是历史上首次发生的在轨卫星碰撞事件.碰撞过程中产生的大量碎片可能会影响太空环境.假定有甲、乙两块碎片,绕地球运动的轨道都是圆,甲的运行速率比乙的大,则下列说法中正确的是

A:甲的运行周期一定比乙的长

B:甲距地面的高度一定比乙的高

C:甲的向心力一定比乙的小

D:甲的加速度一定比乙的大

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答案(点此获取答案解析)

D

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The benefits of keeping a journal(日志)

    If you want to grow, one important thing you should do is keep a journal. It may seem simple, but it can make a big difference in your life. I have been keeping journals for years. Writing all the lessons I learn and all the ideas I get has become a habit for me. ____ Here are some benefits you will get by keeping a journal.

♦ It prevents you from losing an idea. Have you ever gotten an idea and lost it later because you didn't write it down? ____ But then I developed the habit of writing down every idea that came into my mind as soon as possible. If I am away from my computer, I usually write it down on a piece of paper that I bring wherever I go. I will then transfer the idea to the journal in my computer.

♦ It helps you review all the lessons you've learned. By reviewing your journal, you can quickly see the lessons you've learned and the ideas you've gotten. ____ You can use the ideas to propel yourself forward.

____ After keeping a journal for years, you can look back at it and see how far you've gone. Things that were big problems in the past might seem small today. The raw ideas you had in the past have been realized today.

♦ It helps you expand your ideas. When you try to come up with a sentence to express an idea, you are thinking actively about it. ____ In the end, you will expand your ideas.

A.I often experienced that myself.

B.It trains you to express your thoughts.

C.It allows you to see your progress over time.

D.Just use whatever tool you feel comfortable with.

E.Thinking actively helps you connect your idea to another idea.

F.And to be honest, I can't imagine what my life would be like without it.

G.Then you can do whatever necessary to avoid repeating the same mistakes.