*第十一篇　Computer Mouse
　　The basic computer mouse is an amazingly clever invention with a relatively simple design that allows us to point at things on the computer and it is very productive. Think of all the things you can do with a mouse like selecting text for copying and pasting1，drawing，and even scrolling on the page with the newer mice with the wheel. Most of us use the computer mouse daily without stopping to think2 how it works until it gets dirty and we have to learn how to clean it. We learn to point at things before we learn to speak，so the mouse is a very natural pointing device. Qther computer pointing devices include light pens，graphics tablets and touch screens，but the mouse is still our workhorse.
　　The computer mouse was invented in 1964 by Douglas Englehart of Stanford University. As computer screens became more popular and arrow keys were used to move around a body of text，it became clear that a pointing device that allowed easier motion through the text and even selection of text would be very useful. The introduction of the mouse，with the Apple Lisa computer in 1983，really started the computer public on the road to relying on the mouse for routine computer tasks.3
How does the mouse work? We have to start at the bottom，so think upside down for now. It all starts with the mouse ball. As the mouse ball in the bottom of the mouse rolls over the mouse pad，it presses against and turns two shafts. The shafts are connected to wheels with several small holes in them. The wheels have a pair of small electronic light-emitting devices called light-emitting diodes (LED) mounted on either side4. One LED sends a light beam to the LED on the other side. As the wheels spin and a hole rotates by，the light beam gets through to the LED on the other side. But a moment later the light beam is blocked until the next hole is in place. The LED detects a changing pattern of light，converts the pattern into an electronic signal，and sends the signal to the computer through wires in a cable that goes out of the mouse body. This cable is the tail that helps give the mouse its name. The computer interprets the signal to tell it where to position the cursor on the computer screen.
　　So far we have only discussed the basic computer mouse that most of you probably have or have used.5One problem with this design is that the mouse gets dirty as the ball rolls over the surface and picks up dirt. Eventually you have to clean your mouse. The newer optical mice avoid this problem by having no moving parts.
　　词汇:
　　scroll / skrəul/ v. (在显示屏上)上下移动文本 pad /pæd/ n. 垫板
　　mouse pad 鼠标垫板 graphics /'græfiks/ n. 图形，图表
　　tablet /'tæblit/ n. 书写板 graphics tablet 图形书写板
　　workhorse /'wə:khɔ:s/ n. 重负荷工作部件 shaft /ʃa:ft / n. 轴，杆状物
　　emit /i'mit/v. 射出 diode /'daiəud/ n. 二极管
　　cursor /'kə:Sər/ n. 光标 optical /'ɔptikl / adj. 光学的
　　注释:
　　1. copying and pasting: 复制和粘贴
　　2. without stopping to think: 没有停下来想一下。"stop+动词不定式"是"停下来去做某件事"，"stop+动名词"是"停止做某件事"。例如: We stopped to rest for a while. 我们停下来休息一会儿。He stopped smoking. 他停止抽烟。
　　3. ...started the computer public on the road to relying on the mouse for routine computer tasks. 使广大计算机用户开始踏上一条依赖鼠标完成常规计算机工作的道路。computer public: 广大计算机用户。road to 中的to是介词，所以后接动名词relying。
　　4. mounted on either side = mounted on both sides
　　5. So far we have only discussed the basic computer mouse that most of you probably have or have used. 到目前为止，我们只限于讨论大多数人应该拥有或用过的基本型的计算机鼠标。
　　练习:
　　1. Most computer users want to know how the computer mouse works.
　　A Right B Wrong C Not mentioned
　　2. According to the author，general computer users need not to know how the computer mouse was invented.
　　A Right B Wrong C Not mentioned
　　3. The computer mouse derives its name from the cable that goes out its body，which looks like the tail of a mouse.
　　A Right B Wrong C Not mentioned
　　4. The key components of a computer mouse are the two LEDs.
　　A Right B Wrong C Not mentioned
　　5. When an ordinary computer mouse gefs dirty，it has to be replaced with a new one.
　　A Right B Wrong C Not mentioned
　　6. The most durable computer mice on sale are the IBM ones.
　　A Right B Wrong C Not mentioned
　　7. The optical mouse is superior to the basic one in that the former has no moving parts.
　　A Right B Wrong C Not mentioned
　　答案与题解:
　　1. B 题句的意思是大多数计算机使用者都想了解鼠标的工作原理。这与短文的介绍不符。短文第一段第三句说，大多数计算机使用者天天用计算机，却没有想到要了解一下鼠标的工作原理。题句的信息是错误的，故答案为B。
　　2. C 题句表达的意思是，短文作者认为一般计算机使用者无须了解鼠标是如何发明的。题句表达的内容短文中找不到，故答案为C。
　　3. A 题句说鼠标的名称源自鼠标主体拖出的一根看上去像鼠尾巴的电线，这与短文第三段倒数第二句、第三句所介绍的信息相符，所以，本题选项A是正确答案。
　　4. A短文的第三段说到，鼠标的部件有滚动部件如滚球，还有光电装置如二极管等。二极管将光信号转换为电信号，传送到计算机，计算机根据收到的电信号作出相应的反应，因此，二极管是鼠标的主要部件，而滚轮等只是辅助性的机械部件。题句对短文信息的推断是正确的，故答案为A。
　　5. B 题句说鼠标脏了，就得更换新的。这一说法与短文包含的信息不符。第一段第三句和末段倒数第二句都提到，鼠标脏了，可以擦干净再用。题句的信息是错误的，故答案为B。
　　6. C题句说，当前市场上出售的最耐用的鼠标是IBM生产的鼠标。这一说法短文中找不到，故答案为C。
　　7. A末段说到光电鼠标因为没有普通鼠标使用的滚动部件，所以不会吸附灰尘，用不着擦拭，这是一种新型的鼠标。题句是对短文信息的一种合理推断，所以选项A是正确的。

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