第八单元《计算机是什么》以词汇、课文段落以及课后回答问题为主，重点在练习Vocabulary和Question题。

　一、本单元划分为四个部分：
　　1．The ways of conveying and processing information before the invention of computers.
　　2. The functions of computers.
　　3. Two groups of computers.
　　4. A comparison of computers and human minds.

　二、回答问题Question：
　　1. How did primitive men convey information?
　　　They carved word-pictures on the walls of ancient caves and hieroglyphics on stone tablets.

　　2. How did men try to extend the range of his senses and the power of his mind?
　　　They have invented many instruments to help them see better and understand more, such as telescope, microscope, radio, telephone and telegraph.

　　3. Explain the difference between digital computers and analog computers?
　　　Digital computers work by using specific information which is usually in the form of numbers. Analog computers, on the other hand, usually process continuous information.

　　4. Why was Lord Kelvin’s machine regarded as one of the first analog computers?
　　　Because his machine gave continual indications of how tides were to rise and fall, that is, it process continuous information.

　　5. Compare and contrast computers with the minds of men.
　　Computers’ advantages:
　　 1) they can work through a series of problems and make thousands of logical decisions without becoming tired.
　　 2) they can reach solutions to problems in a fraction of time it takes men to do the job.
　　 3) they can replace men in dull, routine tasks.
　　Computers’ disadvantages:
　　 1)they are not creative.
　　 2)they can not exercise value judgements.
　　 3)they have no originality. 4) their achievements are not very great when compared to what the minds of men can do.
第九单元《信鸽是如何找到家的？》以词汇、课文段落以及课后回答问题为主，重点在练习Vocabulary和Question题。

　一、本单元划分为三个部分：
　　1．The question.(1---4)
　　2. The first experiment.(5—7). The second experiment(8—10).
　　3. Conclusion. There are other questions still to be answered.(12—13)

　二、回答问题Question：
　　1. Why do you say the mystery is very old?
　　　Because pigeons have been used as messengers for hundreds of years but their ability to find home is still unknown.

　　2. Why can not we mix up the pigeons’ sense of direction by turning round and round?
　　　Because they use the sun or the earth’s magnetic field to tell direction.

　　3. How can we mix up the pigeons’ direction?
　　　On sunny days we can shift their biological clocks. On cloudy days we can attached a strong little bar magnetic on their backs.

　　4. How did the scientists prove that pigeons have a built-in clock?
　　　In a number of experiments, they attached strong little bar magnetic to one group of pigeons and little brass bars to the other group. Both were taken away from home and let go. On sunny days, none of the magnet-pigeons were fooled. However, on cloudy days, the brass pigeons chose the right direction while the magnet-pigeons acted completely lost.

　　5. Have the scientists answered the old mystery? Explain it.
　　　No, they haven’t fully answered the question. Though they have discovered how pigeons tell direction, (that is, they use the sun or use the earth’s magnet) they haven’t found out how pigeons know where home is.