单选题
Mark Twain once observed that giving up smoking is easy. He knew, because he'd done it hundreds of times himself. Giving up for ever is a trifle more difficult, apparently, and it is well known that it is much more difficult for some people than for others. Why is this so? Few doctors believe any longer that it is simply a question of will power. And for those people that continue to view addicts as merely "weak", recent genetic research may force a rethink. A study conducted by Jacqueline Vink, of the Free University of Amsterdam, used a database called the Netherlands Twin Register to analyse the smoking habits of twins. Her results suggest that an individual's degree of nicotine dependence, and even the number of cigarettes he smokes per day, are strongly genetically influenced. The Netherlands Twin Register is a voluntary database that is prized by geneticists because they allow the comparison of identical twins (who share all their genes) with fraternal twins (who share half). In this case, however, Dr. Vink did not make use of that fact. For her, the database was merely a convenient repository of information. Instead of comparing identical and fraternal twins, she concentrated on the adult fraternal twins, most of whom had completed questionnaires about their habits, including smoking, and 536 of whom had given DNA samples to the register. The human genome is huge. It consists of billions of DNA "letters", some of which can be strung together to make sense (the genes), but many of which have either no function, or an unknown function. To follow what is going on, geneticists rely on markers they have identified within the genome. These are places where the genetic letters may vary between individuals. If a particular variant is routinely associated with a particular physical feature or a behaviour pattern, it suggests that a particular version of a nearby gene is influencing that feature or behaviour. Dr. Vink hopes that finding genes responsible for nicotine dependence will make it possible to identify the causes of such dependence. That will help to classify smokers better (some are social smokers while others are physically addicted) and thus enable "quitting" programmes to be customised. Results such as Dr. Vink's must be interpreted with care. Association studies, as such projects are known, have a disturbing habit of disappearing, as it were, in a puff of smoke when someone tries to replicate them. But if Dr. Vink really has exposed a genetic link with addiction, then Mark Twain's problem may eventually become a thing of the past.
单选题
The author cites the example of Mark Twain to show that
【正确答案】
A
【答案解析】本题问作者引用Mark Twain的例子是为了说明什么。第一段说Mark Twain说戒烟很容易，因为他自己就已戒过数百次了。这是幽默的说法，从反面说明戒烟不容易。作者引用Mark Twain的话引出戒烟难，从而进一步探讨有些人戒烟更难的原因。因此[A]“戒烟不容易”为正确答案。 [B]戒烟需要很强的意志力：从第二段“Few doctors believe…a question of will power．And…to view addicts as merely‘weak’，recent genetic research may force a rethink，”可知意志力不是决定戒烟能否成功的原因和必要条件。作者通过否定一种观点来引出自己真正的观点：戒烟成功与否与基因有关。 [C]一些人为戒不了烟所困扰：第一段虽然也说到烟瘾不容易戒除，隐含人们对戒烟的苦恼，但作者举出例子不是为了说明戒烟的苦恼。 [D]有的人可能注定戒不了烟：首段提到马克·吐温的例子后，作者指出彻底根除烟瘾确实是有点儿困难。接着作者提到：众所周知，对有些人来说，戒烟要比其他人更难。这只是说戒烟难度很大，并且与基因有关。难高大并不代表注定戒不了烟，本项属于过度引申。
单选题
What can be inferred from the third paragraph?
【正确答案】
B
【答案解析】本题问从第三段可以推理出什么?文章第三段第一句指出，“The Netherlands Twin Register is voluntary database that is prized by geneticists because they allow the comparison of identical twins with fraternal twins．”意思是由于这个数据库提供了将双方进行对比的信息，所以遗传学家很重视。说明了一个前提，即把两种双胞胎进行对比是常见的科研手段，所以[B]“两种双胞胎在研究中常常被对比”正确。 [A]异卵双胞胎更受研究人员的重视：过度推理，研究者不采取常规的将两种双胞胎进行对比的方法，只研究异卵双胞胎，这是因为这项研究本身的需要，但不能得出研究人员更重视他们的普遍结论。 [C]同卵双胞胎更容易产生烟瘾：文中未提到。 [D]异卵双胞胎比同卵双胞胎在基因上更相同：与文意相反，同卵双胞胎基因的相同率为100%，异卵双胞胎基因的相同率为50%。
单选题
The word "customized" (Lines 3～4, Paragraph 5) can best be substituted by
【正确答案】
B
【答案解析】本题问第五段第三行至第四行的“customized”一词可被哪个单词替代。从五段“That will help to classify smokers better(some are social smokers while others are physically addicted)and thus enable‘quitting’programmes to be customized，”可知如果能找到影响人们对尼古丁成瘾的基因并查明其原因，则吸烟者可被分为不同类型：一种是与生俱来的，一种是后天养成的。因此戒烟计划也应该因人而异。故[B]“量体裁衣”为正确选项。 [A]多样化；[C]简单化；[D]正当有效：均不能与前一句的意思衔接，故错。
单选题
Dr. Vink's results must be interpreted with care because
【正确答案】
B
【答案解析】本题问为什么须慎重对待Dr.Vink的研究成果。末段“Association studies…have a disturbing habit of disappearing，as it were，in a puff of smoke when someone tries to replicate them，”可知类似的研究可重复性不稳定，也就是说这个实验目前也没有充分的证据。因此[B]“至今仍不可靠”正确。 [A]会对相关实验产生负面影响：文中只说相关实验可重复性不稳定，而没有说此实验会影响相关实验。 [C]会给瘾君子以吸烟的借口；[D]会削弱戒烟运动：Dr.Vink研究的成果很可能给瘾君子以借口从而破坏戒烟，但原文强调的不是因为结果可能带来的影响，而是结果本身的可靠性问题。