—What club do you want to join, Han Mei?

—              .

如图所示，光滑水平面上，质量为m的小球A和质量为 $\frac{1}{3}$ m的小球B通过轻质弹簧相连并处于静止状态，弹簧处于自由伸长状态；质量为m的小球C以初速度v₀沿AB连线向右匀速运动，并与小球A发生弹性正碰．在小球B的右侧某位置固定一块弹性挡板（图中未画出），当小球B与挡板发生正碰后立刻将挡板撤走，不计所有碰撞过程中的机械能损失，弹簧始终处于弹性限度以内，小球B与固定挡板的碰撞时间极短，碰后小球B的速度大小不变，但方向相反，则B与挡板碰后弹簧弹性势能的最大值E_m可能是（   ）

    A meteorite（陨石）almost____(hit) an 80-year-old man named Arthur Pettifer in the UK while he____(work) on the farm. The meteorite was____(big) in the past 26 years in the UK. It weighed（重）one kilo, and might be over 4,000,000,000years old.

    "I heard the big noise in the air. I looked up and saw something falling from the sky to the ground（地面）____ (heavy)," he said, "I had a bad____(feel) about it at that time.____ first I thought it was a plane."

    Meteorites are small things from the space.____ about 3,500 meteorites may fall on the earth every year, only very few of these____(fall) rocks are found. Mr. Pettifer's meteorite is the fifth to fall in the UK____the year of 1939.

    Mr. Pettifer is glad. "When you think about it coming from so far away.____ really is something strange."