阅读下面的短文，文章中有5处空白，文章后面有6组文字，请根据文章的内容选择5组文字，将其分别放回文章原有位置，以恢复文章原貌。
　　The Dangers of Secondhand Smoke
　　Most people know that cigarette smoking is harmful to their health.Scientific research shows that it causes many kinds of diseases.In fact，many people who smoke get lung cancel However, Edward Gilson has lung cancer, and he has never smoked cigarettes.He lives with his wife，Evelyn，who has smoked about a pack of cigarettes a day throughout their marriage. __________.(46)
　　No one knows for sure why Mr. Gilson has lung cancer.Nevertheless，doctors believe that secondhand smoke may cause lung cancer in people who do not smoke because nonsmokers often breathe in the smoke. from other people’s cigarettes.__________ (47)The US Environmental Protection Agency reports that about 53，000 people die in the United States each year as a result of exposure to secondhand smoke.
　　The smoke that comes from a lit cigarette contains many different poisonous chemicals.In the past.scientists did not也ink that these chemicals could harm a nonsmoker’s health. __________ (48)They discovered that even nonsmokers had unhealthy amounts of these toxic(有毒的)chemicals in their bodies.As a matter of fact，almost all of US breathe tobacco smoke at times，whether we realize it or not.For example，we cannot avoid secondhand smoke in restaurants，hotels and other public places.Even though many public places have nonsmoking areas，smoke flows in from the areas where smoking is permitted.It iS even harder for children to avoid secondhand smoke.__________ (49)Research shows that children who are exposed to secondhand smoke are sick more often than children who live in homes where no one smokes and that the children of smokers are more than twice as likely to develop lung cancer when they are adults as are children of nonsmokers.The risk is even higher for children who live in homes where both parents smoke
　　People are becoming very aware of the dangers of secondhand smoke. __________ (50)
　　A. Recently，though，scientists changed their opinion after they studied a large group of nonsmokers.
　　B. The Gilsons have been married for 35 years.
　　C. 111is smoke is called secondhand smoke.
　　D. However, secondhand smoke is dangerous to all people，old or young.
　　E. As a result，they have passed laws which prohibit people from smoking in many public places. .
　　F. In the United States，nine million children under the age of five live in homes with at least one smoker.
　　答案解析
　　46. B. 前一句主要讲的是，Gilson与妻子Evelyn生活在一起，而Evelyn自打他们结婚以来一直是差不多每天一包烟。接下来显然应选表示他们结婚年限的句子。
　　47. C. 前～旬提到，不吸烟者时常吸入他人香烟中冒出的烟，接下来应首选对此烟加以定义的句子。
　　48. A. 前一句讲的是科学家们过去对二手烟的看法，接下来应选表示他们改变观点的句子，因为下一句表明他们所持的观点已与过去截然不同。
　　49. F. 前一句提到了儿童与二手烟的问题。接下来的句子自然仍然与儿童有关。
　　50. E. 前一句讲的是人们逐渐意识到二手烟的危害性，因此接下来应首选表示人们采取措施，禁止公共场所吸烟的句子。