理工类：阅读判断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. Other computer pointing devices include light pens，graphics tablets and touch screens，but the mouse is still our workhorse.3
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.
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 conneected 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 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.5 One 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/skrEul/v.(在显示屏上)上下移动文本 pad/pAd/n.垫板
mouse pad 鼠标垫板 graphics/5^rAfiks/n.图形，图表
tablet/5tAblit/n.书写板 graphics tablet 图形书写板
workhorse/5w\:khC:s/n.重负荷丁作部件 shaft/FB:ft/n.轴，杆状物
emit/i5mit/v.射出 diode/5daiEud/n.二极管
cursor/5kE:sE/n.光标 optical/5CptikEl/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 smoktng.他停止抽烟。
3....started the computer public on the road to relying on the mouse for routine computer tasks：使广大电脑用户开始踏上一条依赖鼠标完成常规电脑工作的道路。computer public：电脑公众。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，我们只限于讨论基本型的电脑鼠标，你们中间多数人也许拥有一个鼠标，也许你们已用过鼠标。