1) It is the business of the scientist to accumulate knowledge about the universe and all that is in it, and to find, if he is able, common factors which underlie and account for the facts that he knows. He chooses, when he can, the method of the “controlled experiment”. If he wants to find out the effect of light on growing plants, he takes many plants, as alike as possible. Some he stands in the sun, some in the shade, some in the dark, all the time keeping all other conditions (temperature, moisture, nourishment) the same. In this way, by keeping other conditions constant, and by varying the light only, the effect of light on the plants can be clearly seen. 2) This method of using “controls” can be applied to a variety of situations, and can be used to find the answers to questions as widely different as “Must moisture be present if iron is to rust?” and “Which variety of beans gives the greatest yield in one season? ”
In the course of his inquiries the scientist may find what he thinks is one common explanation for an increasing number of facts. The explanation, if it seems consistently to fit the various facts, is called a hypothesis. If a hypothesis continues to stand the test of numerous experiments and remains unshaken, it becomes a law.
3) The scientist is always most gratified to find that an underlying “explanation” of many phenomena suggests in its turn the possibility of proving its own accuracy or falsity by a suitably arranged critical experiment. He is also gratified when his “explanation”, if true, points to a new series of experiments designed to answer a new set of questions. For the curiosity of the scientist is never satisfied.
The evidence as to the vastness of the universe and the complexity of its arrangements continues to grow at an amazing rate. The gap between what we know and all that can be known seems not to diminish, but rather to increase with every new discovery. Fresh unexplored regions are forever opening out.
4) The rapidity of the increase of scientific knowledge, in the nineteenth and twentieth centuries, is apt to give students and teachers the impression that no sooner is a problem stated than the answer is forthcoming. A more detailed study of the history of science corrects the impression that fundamental discoveries are made with dramatic suddenness. Even in our present age no less than fifty years separate the discovery of radioactivity from the explosion of the first atomic bomb. Much of the fundamental information which now enables us to control the onset and duration of disease was known a century ago.
5) The teacher, giving his brief accounts of scientific discovery, is liable to forget the long periods of misunderstanding, of false hypotheses and general uncertainty, which almost invariably precede the clear statement of scientific truth. (486 words)
IV. Writing Practice
Directions:
Your are preparing for an English test and are in need of some reference books. Write a letter to the sales department of a bookstore to ask for:
1)detailed information about the books you want,
2)methods of payment,
3)time and way of delivery.
Sample:
Dear Sir / Madam,
Allow me to introduce myself. My name is Li Ming. At present I’m preparing for a national English test. Therefore, I badly need a good dictionary. 能否请您告诉我一些有关词典的情况。您的书店里现在有些什么词典？哪一本最符合我的需要？Besides, I also want to know how I will pay for it. 请您告诉我是用现金还是支票支付书款。By the way, if everything goes smoothly, when can I get the dictionary? 您用什么方式把书转给我呢？
Thank you very much for your time. I’m looking forward to hearing from you soon.
Yours faithfully,
Li Ming
作业：1. 复习本单元内容，配合“复习指导”迅速浏览其中的语法和词汇，为完形、英译汉打好基础。
2. 做“复习指导”中相关 “完形”和“英译汉”练习。
3. 背记本单元应用文。
赠言：有志者事竟成。(Where there is a will there is a way.)
