题目

阅读下面材料，根据其内容和所给段落开头语续写两段，使之构成一篇完整的短文。续写的词数应为150左右。When I was a boy of nine, I used to help Mrs. Long, a retired art teacher who lived across my home. She paid me very little for the help, but she taught me how to paint and promised me, When Christmas comes, I shall have a present for you.I kept wondering what it would be. The boys I played with had baseball gloves, ice skates and bicycles. I hoped that Mrs. Long would buy any one of them for me.But it would hardly be ice skates, I reasoned with myself 雷达是重要的军事装备．如图所示，若雷达向飞机发出的微波从发射到反射回来的时间为52 μs(1 μs＝10－6 s)，微波的传播速度等于真空中的光速，则微波的传播速度大小为________ m／s，此时飞机与雷达的距离为________ m．