Although man has known about 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 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, soapy fibers（滑腻的纤维）。
Scientists do not know why the rock can be separated easily into threads（线）,but they have found thousands of uses for this fireproof material, often called the “cloth of stone”.
1. The title that best expresses the main idea of the passage is _____.
A. Asbestos mined in Canada          B. Fireproof matter
C. A “wonder” mineral               D. A new roofing material
2. Johns proved his ability （能力）as a salesman by_____.
going into the roofing business
carrying asbestos from Italy
sending a trained scientist
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 bums easily               D. It is unusually heavy
4. The author’s main purpose in writing this passage is to______.
show the need for more scientists
compare asbestos with other minerals
increase the sales of asbestos
present facts about asbestos