问题 问答题 简答题

潜水均衡方程式是如何建立的?有何实际意义?

答案

参考答案:

潜水的均衡方程式是根据潜水的补给量和排除量的差建立起的。

根据这一个方程式可以大致知道一个地区的潜水埋藏情况,以及取水情况,以指导地下水的开采活动。

阅读理解

阅读理解。

    Although man has known asbestos for many hundreds of years, it was not until 160 years ago that it was

mined for the first time on the North American continent.H.W.Johns, owner of a New York City Supply Shop

for roofers, was responsible for (对…负责) the opening of that first mine.

     Mr. Johns was given a piece of asbestos which had been found in Italy. He experimented with the material

and then showed its surprising powers to his customers. After putting on a pair of asbestos gloves, which

looked much like ordinary work gloves, he took red-hot coals from the fireplace and played with them in his

hands. How astonished the customers were to discover that he was not burned at all.You can well imagine that

he had increasing business in asbestos roofing materials. However, because it was very expensive to transport

(carry) them from Italy to the United States, Mr. Johns sent out a young scientist to seek a source nearer home.

This young man found great vein (岩脉), in the province of Quebec in Canada.

    Ever since 1881 Quebec has led the world in the production of this unusual mineral, which is made up of

magnesium, silicon, iron, and oxygen.When it is mined, the asbestos is heavy, just as you would expect a

mineral to be. When it is separated, a strange thing happens; the rock breaks down into fine, soft, soapy

fibres (纤维).

    Scientists do not know why the rock can be separated easily into threads (线), but they have found

thousands of uses of this fireproof material, of the so-called "cloth of stone".

1. Which title best expresses the main idea of this passage? [ ]

A. Asbestos mined in Canada

B. Fireproof matter

C. A "wonder" mineral

D. A new roofing material

2. Johns proved his ability as a salesman by _____. [ ]

A. going into roofing business

B. carrying asbestos from Italy

C. sending a trained scientist

D. showing the use of asbestos gloves

3. Which is the most important character of asbestos that the author wants to show us? [ ]

A. It is like thread.

B. It feels soapy.

C. It burns easily.

D. It is unusually heavy.

4. The author's main purpose in writing this passage was to _____. [ ]

A. show the need for more scientists

B. compare asbestos with other minerals

C. increase the sales of asbestos

D. present facts about asbestos

名词解释