题目

组成DNA结构的基本成分是( ) ①核糖 ②脱氧核糖 ③磷酸 ④腺嘌呤、鸟嘌呤、胞嘧啶 ⑤胸腺嘧啶 ⑥尿嘧啶 A．①③④⑤                B．①②④⑥ C．②③④⑤                D．②③④⑥   答案：C  DNA的基本组成单位是脱氧核苷酸，脱氧核苷酸由碱基、磷酸、脱氧核糖组成，碱基包括腺嘌呤、鸟嘌呤、胞嘧啶、胸腺嘧啶。阅读理解 　　Within a few short years, girls in Europe have become heavier smokers than boys, for reasons experts still fail to understand, according to a British study presented(递交)last week to an international conference on smoking. 　　Anti－smoking activists(积极分子)at the second“Tobacco or Health”conference in the Canary Islands pointed out that while adults(grown－ups) were giving up smoking in ever growing numbers, more and more young people were taking up the habit, particularly girls. 　　One 15－year－old in four is a regular smoker, according to a study made in 27 countries in Europe and the United States, Canada and Israel－by Edinburgh University together with the World Health Organization. 　　In Western Europe, girls were more likely than boys to smoke. In Germany or in England, one third of the girls were smokers compared to one in four boys. In Eastern Europe, the girls“still fall beind”those in the Western Europe but were“catching up”quickly, said the study. 　　The study dealt with the behaviour(行为)of 15－year－olds in seven European countries over four year－periods between 1986 and 1998. 　　The percentages(百分比)of young women smoking went from 17 percent to 36 percent in Austria, from 17 percent to 28 percent in Norway, from 21 percent to 28 percent in Hungary. 　　In the seven countries and regions studied－Austria, Finland, Hungary, Norway, Sweden, Switzerland and Wales－more girls smoked than boys in 1998, with the exception of Hungary. 1．According to the article, more and more ________ in Europe were giving up smoking. [　　] A．adultsB．boys C．girlsD．old men 2．The number of boy smokers is ________ that of girl smokers. [　　] A．larger thanB．as large as C．smaller thanD．as small as 3．The study was made by ________. [　　] A．Edinburgh University B．the World Health Organization C．Oxford University D．Edinburgh University and the World Health Organization 4．The country where the number of young women smokers increases fastest is ________. [　　] A．NorwayB．Austria C．HungaryD．Sweden 5．The Main idea of the passage is ________. [　　] A．to introduce something about girl smokers in Europe B．to report something interesting happened in England C．to describe the present condition of European smokers D．to warn young people around the world against smoking