题目内容
简述广播事业发展的一般历程。
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I don’t mind you (smoke) ______ in the room.
简述文件系统的结构。
位示图可以用来指示磁盘存储空间的使用情况，一个磁盘组的分块确定后，根据可分配的总块数决定位示图由多少个字组成，位示图中的每一位与一块对应，“1”状态表示相应块已______，“0”状态表示该块______。
Trees are useful to man in three important ways: they provide wood and other products; they give him shade; and they help to prevent droughts and floods. Unfortunately, in many parts of the world, man has not realized that the third of these services is the most important. In his eagerness to make money from trees, he has cut them down in large numbers, only to find that without them he has lost the best friends he had. And besides, he is usually too careless to plant and look after new trees. So the forests slowly disappear. This does not only mean that man will have fewer trees. The results are even more serious: for where there are trees, their roots break up soi — allowing the rain to sink in — and also bind the soil, thus preventing it from being washed away easily; but where there are no trees, the rain falls on hard ground and flows away, causing floods and carrying away the rich top-soil. When all the top-soil is gone, nothing remains but worthless desert. The origin of floods and starvation in some countries is ______.
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