2. 职称英语
  3. A pilot cannot fly a plane by sight alone. In many conditions, such as flyin

A pilot cannot fly a plane by sight alone. In many conditions, such as flyin

游客2024-01-01  61
问题     A pilot cannot fly a plane by sight alone. In many conditions, such as flying at night and landing in dense fog, a pilot must use radar, an alternative way of navigating. Since human eyes are not very good at determining speeds of approaching objects, radar can show a pilot how fast nearby planes are moving. The basic principle of radar is exemplified by what happens when one shouts in a cave. The echo of the sounds against the walls helps a person determine the size of the cave. With radar, however, the waves are radio waves instead of sound waves. Radio waves travel at the speed of light, about 300, 000 kilometers in one second. A radar set sends out a short burst of radio waves: Then it receives the echoes produced when the waves bounce off objects. By determining the time it takes for the echoes to return to the radar set, a trained technician can determine the distance between the radar set and other objects. The word "radar," in fact, gets its name from the term "radio detection and ranging." "Ranging" is the term for detection of the distance between an object and the radar set. Besides being of critical importance to pilots, radar is essential for air traffic control, tracking ships at sea, and for tracking weather systems and storms.  [br] Which of the following would most likely be the topic of the next paragraph 1?
选项 A、Other uses of radar.
B、Uses of sonar technology.
C、Other technology used by pilots.
D、A history of flying.
答案 B
解析 推断题型通读全文可见本段开始介绍了飞行员在驾驶飞机时的局限，于是借助于雷达；接着介绍了雷达的工作原理，名字的来源，及其他功用等；由此判断有关介绍雷达的内容已告一段落，下一段应不会再讲雷达的其他功用(排除选项A)；本段因是围绕雷达来写，尽管提到雷达对飞行员起到举足轻重的作用，但目的不是向飞行员介绍不同种类的科学技术(排除选项C)；本段的目的也不是为了介绍飞行史(排除选项D)；因此只有选项B (使用声纳/声波定位仪这一技术)较为可能；声纳与雷达的工作原理近似，但更多用于水中；由此可假定本段讲了在空中和陆地上雷达的功用，下一段可能要讲解水中利用这一原理——声纳的应用；选项B为答案。
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