19．Smoking bans in public places are linked with falls in childhood asthma （哮喘） attacks and preterm births （早产），according to the biggest analysis of the influence of public smoking bans on child health．The finding should remove fears that such laws could have the opposite effect because they may lead people to smoke more at home．
Several countries，such as Japan and Australia，have tightened laws on smoking in public places over the last few years．Meanwhile，some countries，such as the Netherlands and Germany，still allow smoking in pubs and restaurants．Only about half of US states have comprehensive bans，and there are few restrictions in poorer nations．
Opponents often claim that bans could result in people smoking more at home，which would be worse for their children's health．Asthma is one of the main concerns as second-hand smoke harms children's airways in several ways．
Researchers led by Jasper Been at Maastricht University Medical Centre reviewed as many as 11studies that examined how hospital admissions for childhood asthma and preterm births changed after smoking bans came in．The studies involved more than 2.5million births，and nearly 250，000hospital admissions for asthma．
The result shows that both asthma admissions and preterm birth rates fell by about 10percent within a year after smoking restrictions were carried out．The effect on preterm births could also have been caused by pregnant women being more likely to quit or cut down following a public ban，says Been．But Been also says the studies could not completely prove that smoking bans directly caused these changes．However，as a matter of fact，because the analysis included several smoking bans introduced in different countries in different years，and most saw health improvements．
Such findings are useful for countries and states where there is ongoing debate about how strict smoking bans should be，especially as hospital care for premature babies is so expensive．This might be one of the most important things to know in order to strengthen legislation （立法）．
Other studies have shown that rates of heart attack and stroke also tend to fall after smoking bans are introduced．
21．According to the passage，some oppose smoking bans in public places becauseB．
A．they have much difficulty in quitting smoking
B．they believe it will cause people to smoke more at home
C．smoking bans contributing to health can't be proved
D．the laws might cause opposite effect on smokers
22．Which is NOT the proper effect of the result of research by Jasper Been？C
A．People would accept the laws on smoking bans in public places．
B．More and more countries and states will strengthen smoking bans．
C．Hospital care for premature babies and asthma will be cheaper．
D．Pregnant women will be more likely to follow public smoking bans．
23．Which of the following statements about Been's research is TRUE？D
A．It also proves smoking bans lead to falls of heart attack and stroke．
B．It is related to millions of asthma hospital admissions and births cases．
C．It offers conclusive evidence about smoking bans causing health benefits．
D．It is supposed to prove the effect of smoking bans in public places on health．
24．In their analysis，the researchers drew their conclusion byA．
A．comparison
B．experimenting
C．questionnaire
D．example．
分析 本文是一篇社会文化类阅读，属于说明文，禁止在公共场合吸烟是与儿童哮喘发作和早产有关的，根据分析公共场所吸烟禁令对孩子健康的最大影响，应该这样的法律会产生相反的效果，因为他们可能会导致人们更多的在家里抽烟．
解答 21．B 细节理解题．根据文章第3段"Opponents often claim that bans could result in people smoking more at home，which would be worse for their children's health"可知，反对者声称戒令会导致人们在家里多抽烟，从而更加影响孩子的健康，故选B项．
22．C 细节理解题．Jasper Been的研究结果表明A、B、D三项都是正确的；而哮喘和早产的住院治疗费用的高低与此研究结果无关，故选C项．
23．D 推理判断题．根据Researchers led by Jasper Been at Maastricht University Medical Centre reviewed as many as 11studies that examined how hospital admissions for childhood asthma and preterm births changed after smoking bans came in可知，由于人们对于公共场所戒烟是否会对健康造成影响存有疑虑，所以Been才会率领研究者进行研究，故选D项．
24．A 推理判断题．根据第4、5段However，as a matter of fact，because the analysis included several smoking bans introduced in different countries in different years，and most saw health improvements．以及The effect on preterm births could also have been caused by pregnant women being more likely to quit or cut down following a public ban，says Been．But Been also says the studies could not completely prove that smoking bans directly caused these changes．可知，Been的研究主要是分析比较了不同国家戒烟前后儿童哮喘和早产住院数据而得出的结论，所以研究者采用的主要办法就是比较，故选A项．
点评 本文是一篇社会文化类阅读，题目涉及多道细节理解题，推理判断题．做题时学生应仔细阅读原文，把握文章主要内容，联系文章上下文内容并结合所给选项含义，从中选出正确答案，一定要做到有理有据，切忌胡乱猜测．
