题目

   阅读下面材料，在空白处填入适当的内容或括号内单词的正确形式。 One day, my brothers and I    61   (come) back from the islands. All at once, the sky was covered with dark clouds and we were in a terrible storm.  62  the wind and waves we went nearer and nearer to the horrible edge of the whirlpool, but moment after   63  passed, I was still safe. I noticed that the  64  (heavy) objects went down more quickly than the smaller, lighter ones, so I tied   65  (me) to a barrel to help me float. Luckily, I survived. Hiking trips can be  66  (co 有一直升机停在200 m高的空中静止不动，有一乘客从窗口由静止每隔1秒释放一个钢球，则关于钢球在空中的排列情况的说法正确的是(　　) A．相邻钢球间距离相等 B．越靠近地面，相邻钢球的距离越大 C．在落地前，早释放的钢球速度总是比晚释放的钢球的速度大 D．早释放的钢球落地时的速度大