Doctors believe that second-hand smoke may cause lung cancer in people who do not smoke.
Nonsmokers often breathe in the smoke from other people' s cigarettes. This is second-hand smoke. The US Environmental Protection Agency (美国环保局) reports that about fifty-three thousand people die in the United States each year as a result of exposure to second-hand smoke.
It is harder for children to avoid second-hand smoke. In the United States, nine million children under the age of five live in homes with at least one smoker. Research shows that these children are sick more often than children who live in homes where no one smokes. The damaging effects of second-hand smoke on children also continue as they grow up. The children of smokers are more than twice as likely to develop lung cancer when they are adults as 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 danger of second-hand smoke. As a result, they have passed laws that prohibit people from smoking in many public places. Currently, 45 states in the US have laws that restrict smoking. The most well-known law doesn' t allow people to smoke on short native airline flights, i. e. flights within the country.
Compared with nonsmokers’ children, the children whose parents both smoke are likely to
根据第三段最后两句“The children of smokers are more than twice as likely to develop lung cancer…The risk is even higher for children who live in homes where both parents smoke．”可知，与非吸烟者的孩子相比，吸烟者的孩子有两倍多的可能会患肺癌，而家里父母双方都吸烟的话，其孩子患肺癌的风险会更高。由此可推知，父母双方都是吸烟者的话，相比非吸烟者的孩子，其孩子更有可能患肺癌。故选C。
Why are there laws made against smoking in public places in the US?
根据最后一段前三句“People are becoming very aware of the danger of second-hand smoke．As a result，they have passed laws that prohibit…in the US have laws that restrict smoking．”可知，由于人们越来越意识到二手烟的危害，因此他们制定了禁止在公共场合吸烟的法律，目前在美国就有45个州出台了限制吸烟的法律。故选A。
Which of the following statements is TRUE?
根据第三段倒数第二句“The children of smokers are more than twice as likely to develop lung cancer…”可知，吸烟者的孩子长大后患肺癌的概率是非吸烟者的孩子的两倍多，但并没有说吸烟者的孩子数量是非吸烟者的孩子数量的两倍多，所以A、C两项错误。根据最后一段最后一句“The most well-known law doesn’t allow people to smoke on short native airline flights…”可知，美国法律规定，在国内短途航班上不允许人们吸烟，所以B项正确。通读全文可知，文中并没有比较一手烟和二手烟哪个危害更大，所以D项错误。故选B。
From the passage we can conclude that________.
根据第三段第一句“It is harder for children to avoid second-hand smoke．”和下文内容可知，孩子更难避免二手烟的影响，父母双方都吸烟的话，其孩子长大后相比那些父母不吸烟的孩子来说更有可能患肺癌。由此可推知，孩子遭受二手烟的影响很大。故选D。根据最后一段第一句“People are becoming very aware of the danger of second-hand smoke．”可知，B项错误；选项A、C在文中并未提及。
The word "restrict" in the last paragraph is closest in meaning to________.
根据最后一段第二、三句可知，美国出台了禁止人们在公共场合吸烟的法律，这是对吸烟范围的一种限制，而不是控制人们吸烟，所以此处表达的是“目前美国有45个州制定了限制吸烟的法律”。restrict意为“限制”，limit(限制)与其意思最为接近。故选A。