单选题在本届全国足球联赛的多轮比赛中，参赛的青年足球队先后有六个前锋，七个后卫，五个中卫，两个守门员。比赛规则规定：在一场比赛中同一个球员不允许改变位置身份，当然也不允有一个以上的位置身份，同时，在任一场比赛中，任一球员必须比赛到终场，除非受伤。由此可得出结论：联赛中青年足球上场的共有球员20名。 以下哪项为真，最能削弱以上结论?( )

单选题某市繁星商厦服装部在前一阵疲软的服装市场中打了一个反季节销售的胜仗。据统计，繁星商厦皮服的销售额在6、7、8三个月连续成倍数增长，6月527件，7月1269件，8月3218件。市有关主管部门希望在今年冬天向全市各大商场推广这种反季节销售的策略，力争今年11、12月和明年1月全市的夏衣销售有一个大的突破。以下哪项如果为真，能够最好地说明该市有关主管部门的这各希望可能会遇到麻烦?

单选题Scientists now believe that artificial-hip implants, previously thought to be safe, may actually increase the risk of cancer in recipients after about 45 years of use. Though these implants do improve the quality of recipients' lives, the increased risk of cancer is an unacceptable price to pay for these improvements. Therefore, they should be banned. Which of the following, if true, is the strongest counterargument to the argument above?

单选题在中国北部有这样两个村落，赵村所有的人都是在白天祭祀祖先，李庄所有的人都是在晚上才祭祀祖先，我们确信没有既在白天也在晚上祭祀祖先的人。我们也知道李明是晚上祭祀祖先的人。依据以上信息，能断定以下哪项是对李明身份的正确判断?

单选题根据大陆漂移假说，现在许多分离的陆地在史前时是一块巨大的陆地的一部分。由于地壳运动，这块陆地开始分裂。由这个理论可以猜想南美洲的东海岸原来跟非洲的西海岸是连在一起的。 以下哪个发现最能支持上述猜想?

单选题Mayor Smith, one of our few government officials with a record of outspoken, informed, and consistent opposition to nuclear power plant construction projects, has now declared herself in favor of building the nuclear power plant at Littletown. If someone with her past antinuclear record now favors building this power plant, then there is good reason to believe that it will be safe and therefore should be built. The argument is vulnerable to criticism on which one of the following grounds?

单选题李惠的个子比胡戈高；张凤元的个子比邓元高；邓元的个子比陈小曼矮；胡戈和陈小曼的身高相同。 如果上述断定为真，以下哪项也一定为真?

单选题物种灭绝是大自然的规律。据科学家估计，在人类使用最原始的工具以前，地球上曾经存在的物种就已经灭绝了大半。大自然的这种不断产生和消灭物种的恒常过程被那些指责人类使用技术而影响了环境，并由此而造成新近的物种灭亡的人忽视。这些人必须明白：现代灭绝的物种即使没有人类技术的应用现在也会灭绝的。 以下哪项指明了上文中的推理错误?

单选题The town of Greenfield recently instituted a substantial supplementary tax on all households, whereby each household is taxed in proportion to the volume of the trash that it puts out for trash collectors to pick up, as measured by the number of standard-sized garbage bags put out. In order to reduce the volume of the trash on which their tax bill is based, Greenfield households can deliver their recyclable trash to a conveniently located local commercial recycling center, where such trash is accepted free of charge. The supplementary tax provides some financial incentive to Greenfield households to do each of the following EXCEPT

单选题实验发现，孕妇适当补充维生素D可降低新生儿感染呼吸道合胞病毒的风险。科研人员检测了156名新生儿脐带血中维生素D的含量，其中54％的新生儿被诊断为维生素D缺乏，这当中有12％的孩子在出生后一年内感染了呼吸道合胞病毒，这一比例远高于维生素D正常的孩子。以下哪项如果为真，最能对科研人员的上述发现提供支持?

单选题在一个物质过剩的世界里却有人因为物质短缺而死去，这种道德上的令人厌恶和智力上的荒谬愚蠢，令我感到震惊和羞耻。 下面哪一项是上面这句话的明显含义? A．在一个物质过剩的世界里，有人因物质短缺而死去，是因为他过于懒惰。 B．在一个物质过剩的世界里，有人因物质短缺而死去，是因为他过于愚蠢。 C．从道德和智力这两个层面而言，我们本来应该设计出一种分配制度，以便让每个社会成员都过上体面有尊严的生活。 D．在一个物质过剩的世界里，有人因物质短缺而死去，是因为他在性格上有缺陷。

单选题食用某些食物可降低体内自由基，达到排毒、清洁血液的作用。研究者将大鼠设定为实验动物，分为两组，A组每天喂养含菌类、海带、韭菜和绿豆的混合食物，B组喂养一般饲料。研究观察到，A组大鼠的体内自由基比B组显著降低。科学家由此得出结论：人类食入菌类、海带、韭菜和绿豆的混合食物同样可以降低体内自由基。 以下哪项最可能是上述论证所假设的?

单选题网络咖啡屋，或者是网吧目前在都市非常流行，不少专家觉得这是一个很好的服务方向，很有市场前景。但实际上，网络咖啡屋和网吧的经营遇到了很多闲难，其中之一就是电信部门网络服务基础收费太高，按照网络咖啡屋和网吧最初定的价格，就是加上酒水方面的利润，总体上也还是亏本。有些网络咖啡屋和网吧的经营者进行了量一本一利的计算后，准备全面提高网络服务和酒水的价格，来维持自身的生存和发展。 以下哪项如果为真，能有力地对上述措施提出质疑?

单选题很多冷藏食品腐坏的原因是这些食品在冰箱搁板后面变坏却看不见。那么为何不使用能旋转的圆形搁板呢?因为圆形搁板的缺陷是搁板上的东西可能从搁板边上掉到后面的角落去。 在反对引入旋转搁板的论证中，下面哪个是被预先假定的?

单选题某市主干道上摩托车车道的宽度为2米，很多摩托车经常在汽车道上抢道行驶，严重破坏了交通秩序，使交通事故频发。很多人向政府提出建议：应当将摩托车道拓宽，让骑摩托车的人有较宽的车道，从而消除抢道现象。 下列哪项如果为真，最能削弱上述观点?

单选题In the 1980 United States census, marital status was described under one of five categories: single, now married (but not separated), separated, divorced, widowed. In the category "separated," including both those who were legally separated and those who were estranged and living apart from their spouses, one million more women than men were counted. Which of the following, if true, provide(s) or contribute(s) to an explanation for this result? Ⅰ. There are more women of marriageable, age than men of marriageable age in the United States. Ⅱ. More of the separated men than separated women in the United States could not be found by the census takers during the census. Ⅲ. Many more separated men than separated women left the United States for residence in another country.

单选题Government department head: We already have a code of ethics that companies doing business with the department are urged to abide by. The fact that virtually all of the companies have agreed to abide by it indicates that it is successful. Therefore, neither stronger ethics regulations nor enforcement mechanisms are necessary to ensure ethical behavior by companies doing business with the department. Which of the following, if true, casts most doubt on the department head's conclusion? (A) The code of ethics applies only to companies that do business with the department. (B) The code of ethics was instituted only after it was discovered that several companies had committed serious violations of ethics in their business with the department. (C) A government investigation found that most of the companies that agreed to abide by the department's code of ethics are not complying with it. (D) A survey of major companies found that several companies stopped doing business with the department because they did not want to agree to abide by the code of ethics. (E) A study of codes of ethics for companies found that the codes are most effective when the top executives of companies that agree to abide by them are fully committed to following them.

单选题对一批企业的调查显示，这些企业总经理的平均年龄是57岁，而在20年前，同样的这些企业的总经理的平均年龄大约是49岁。这说明，目前企业中总经理的年龄呈老化趋势。 以下哪项，对题干的论证提出的质疑最为有力?

单选题一位经济学家提出，把污染型工业从发达国家转移到发展中国家，发达国家因自然环境的改善而受益。发展中国家虽然环境受到污染，但在解决就业、增加税收等方面得到补偿。因此，双方的境遇都有所改善，从而全球的总福利得到增加。 以下哪项是这位经济学家论述的假设?

单选题地球两极地区所有的冰都是由降雪形成的。特别冷的空气不能保持很多的湿气，所以不能产生大量降雪。近年来，两极地区的空气无一例外地特别冷。 　　以上信息最有力地支持以下哪一个结论？