题目

下列叙述中正确的是（   ） A .   漂白粉中的有效成分为次氯酸钙，在空气中可以长时间放置而不变质 B . 二氧化硅是将太阳能转变为电能的常用材料 C . 美国纽约冬季城市供暖使用的主要能源是天然气，天然气属于不可再生能源 D . 虎门销烟中用到了大量的生石灰，将生石灰投入销烟池的海水中，海水开始翻腾，这是一个物理变化阅读理解 阅读下列短文，从每题所给的四个选项(A、B、C、D)中，选出最佳选项。 　　One of the best-known proverbs must be “early to bed, early to rise, makes a man healthy, wealthy, and wise.” The promises of health, wealth, and wisdom to those who join the ranks of the early retirers and risers must be particularly appealing to many people in our contemporary society. There is no doubt that one of the greatest concerns of modern man is his health. It is estimated that in the Unites States $ 200 billion are spent on health care each year. The medical field has grown into such a big business that it employs 4.8 million people; and it appears that in many places more staff is needed to meet the demands of the people who are concerned about their physical well-being. 　　Much more interest has been shown in preventive medicine in recent yeas. This is probably due in part to the increasing costs of medical treatment, but the writings of such people as Dr. Keneth Cooper have also played an important role. In his book Aerobics, Dr. Cooper communicated his message of the benefits of exercise so effectively many other authors have followed in his trail, and literally millions of readers have put on their sports shoes and taken to the highways and byways of America. A recent survey showed that over 17 million people are jogging. Many of these are so serious they have trained themselves to run the 26 miles and 385 yards: of the hard and tiring marathons (马拉松) that are sponsored (发起) all over the country. The last time I was in Honolulu, I was amazed to see hundreds of people, young and old, running for their lives, and I discovered many of them have run in the Hawaiian Marathon. 　　Exercise has also become a major part of conversation. At a dinner party recently, the president of a bank asked me, “You look like a runner; how far do you run each day?” A few days later when I appeared on a national television show, the host suddenly asked me if I was a regular runner. On both occasions the conversation turned to the subject of exercise and I found, as I have found whenever I have traveled recently, that this is a subject on many people's minds. Of course, there are still many people who are less than enthusiastic about exercise. They appreciate the philosophy of Robert M. Hutchins who said, “Whenever the thought of exercise occurs to me, I lie down till it passes.” 1．The first paragraph indicated that medical workers ________. [　　] A．are in great demand B．make a lot of money C．are concerned with their won health D．like sports more than ordinary people 2．In the United State medical treatment is ________. [　　] A．very effectiveB．cheap C．insufficientD．expensive 3．Aerobics is a book about ________. [　　] A．medicineB．driving C．exerciseD．marathon 4．The examples of conversation in the last paragraph are used ________. [　　] A．to prove that people are tired of old conversation B．to prove that the writer was a good runner C．to show people's interest in exercise D．to show the writer's love for travel