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".

4. 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

5. Johns proved his ability （能力）as a salesman by_____.

A. going into the roofing business

B. carrying asbestos from Italy

C. sending a trained scientist

D. showing the use of asbestos gloves

6. 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

7. The author's main purpose in writing this passage is 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

Two Englishmen were traveling in France when a policeman stopped their car and gave it a search. He found a bag of white powder, which looked suspicious（可疑的）. "Drogue?" asked the policeman who was sensitive to heroin（海洛因）. "Yes, dog", the two replied, having the least idea of their misunderstanding of the French