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当前学科：室内覆盖系统
题目：
填空题
隧道信号覆盖也可以用小的平板天线，适合安装在（）.
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As Christmas is coming, there are presents to be bought, cards to be sent, and rooms to be cleaned. Parents are ___1___ with difficult jobs of hiding presents from curious young children. If the gifts are large, this is sometimes a real ___2___. On Christmas Eve, young children find the excitement almost unbearable. They are torn between the wish to go to bed early so that Father Christmas will bring their presents quickly and the wish to stay up late so that they will not miss the fun. The wish for gifts usually proves stronger. But though children go to bed early, they often lie awake for a long time, hoping to get a short ___3___ at Father Christmas. Last Christmas, my wife and I successfully hid a few large presents in the storeroom. I ___4___ the moment when my son, Jimmy, would ask me where that new bike had come from, but ___5___ he did not see it. On Christmas Eve, it took the children hours to go to sleep. It must have been nearly ___6___ when my wife and I went quietly into their room and began filling stockings. Then I pushed in the ___7___ I bought for Jimmy and left it beside the Christmas tree. We knew we would not get much sleep that night, for the children were ___8___ to get up early. At about five o’clock the next morning, we were woken by loud sounds coming from the children’s room — they were shouting excitedly! Before I had time to get out of bed, young Jimmy came riding into the room on his new bike, and his sister, Mary, followed close behind pushing her new baby carriage. Even the baby arrived. He moved ___9___ the hands and knees into the room dragging a large balloon behind him. Suddenly it burst. That woke us up ___10___. The day had really begun with a band! ___8___内应选（）
氧中毒
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氧化还原反应的实质是什么？
已知两正弦量 i1 ＝10sin(314t+90°)安,i2＝10sin(314t+30°)安，则（ ）。