In the United States, newspaper reports tell of "crime in the streets" every day. (36) , all too often such stories have made many people think that (37) are so dangerous that they should be (38) . However, this is not necessarily the (39) . If an individual is careful wherever he goes, the (40) of having a misfortune in any large city are (41) small. Besides, the police have also given many tips to help people be on (42) against any possible attack. In general, when moving about a city at night, it is (43) to keep to the more traveled and better lighted streets. If you must travel through areas of a city that are considered dangerous, (44) . Avoid parks in the night since they are too likely to be deserted. Most cities have special telephone numbers to report a fire or to call the police. (45) . If the number is not posted, you can reach the police or fire department by calling the operator on the telephone. (46) .
查看答案
清晰的结构是DBMS具有______的一个必要条件。
常用的模式分解的等价标准要求分解是具有______的和要求分解是保持函数依赖的。
There is no living creature that does not need sleep or completerest every day. If you want to know why, just try go without sleep for a long period 67. ______of time. You will discover that your mind and body would become tired 68. ______to work properly. You would find it hard to think clearly or concentrate in 69. ______your work. So sleep is quite simply the time when the cells of your bodyrecover from the work of the day and build up supplies of energy forthe latter period of activity. 70. ______ One of the things we all know about sleep is that we areunconscious in sleep. We do not know what is going up around us. But 71. ______that doesn’t mean the body stops all activity. The important organs stop 72. ______to work during sleep, but most of the body functions are slowed down. For example, our breathing becomes quicker and deeper. The heart 73. ______beats more slowly, and the blood pressure is lower. Our arms and legsbecome limp (柔软的) and muscles are rest. It would be impossible for 74. ______our body to relax to such an extent if we were awake. So sleep does forus that the most quiet rest can not do. 75. ______ And even though you are unconscious, many of your reflexes (习惯性思维) still work. For instance, if someone tickles (使……觉得痒)your foot, you will put them away in your sleep. You do this without 76. ______knowing it.
互联网的计算机是分布在不同地理位置的多台______的“自治计算机”。