47. Why are some lifestyle factors considered extremely important?
- A. They may shorten the process of cell division.
- B. They may determine how genes function.
- C. They may affect the lifespan of telomeres.
- D. They may account for the stresses on cells.
答案：B
答案句：Even though you were born with a particular set of genes, the way you live can influence how they express themselves. Some lifestyle factors may even turn genes on or shut them off.
参考译文：即使你生来就带有特定的基因，你的生活方式也能影响它们如何表达。一些生活方式因素甚至可能开启或关闭基因。
定位线索：题干“Why are some lifestyle factors considered extremely important”→答案句取自第1段“the way you live can influence how they express themselves”；文中“the way you live”对应题干“lifestyle factors”；文中“influence how they express themselves”和“turn genes on or shut them off”对应选项B“determine how genes function”。
解析：题干问生活方式因素为何极其重要，答案句指出生活方式能影响基因如何表达，甚至能开启或关闭基因，即生活方式能决定基因的功能，对应选项B。选项A“缩短细胞分裂过程”无中生有，文中未提及生活方式缩短细胞分裂；选项C“影响端粒寿命”是后文内容，但题干问的是生活方式因素重要的原因，且答案句未提及端粒；选项D“解释细胞压力”无中生有，文中未提及。
48. What have the author and his colleagues discovered about telomeres?
- A. Their number affects the growth of cells.
- B. Their length determines the quality of life.
- C. Their shortening process can be reversed.
- D. Their health impacts the division of cells.
答案：C
答案句：We've devoted most of our careers to studying telomeres, and one extraordinary discovery from our labs is that telomeres can actually lengthen.
参考译文：我们职业生涯的大部分时间都致力于研究端粒，而我们实验室的一个非凡发现是：端粒实际上可以变长。
定位线索：题干“What have the author and his colleagues discovered about telomeres”→答案句取自第2段“one extraordinary discovery from our labs is that telomeres can actually lengthen”；文中“lengthen”对应选项C“be reversed”（缩短过程可被逆转）。
解析：题干问作者及其同事关于端粒的发现，答案句明确说他们的发现是“端粒实际上可以变长”。前文提到端粒随细胞分裂而缩短，而变长意味着缩短过程可以被逆转，对应选项C。选项A“数量影响细胞生长”无中生有，文中未提及端粒数量；选项B“长度决定生活质量”偷换概念，文中说端粒长度影响细胞衰老，未说决定生活质量；选项D“端粒健康影响细胞分裂”是文中已有事实，但不是作者的发现，且“健康”一词不准确。
49. What have scientists learned about cynical hostility?
- A. It may lead to confrontational thought patterns.
- B. It may produce an adverse effect on telomeres.
- C. It may cause people to lose their temper frequently.
- D. It may stir up agitation among those in long lines.
答案：B
答案句：Scientists have learned that several thought patterns appear to be unhealthy for telomeres, and one of them is cynical hostility. … People who score high on measures of cynical hostility tend to get more heart disease, metabolic disease and often die at younger ages. They also have shorter telomeres.
参考译文：科学家们已经了解到，几种思维模式似乎对端粒不健康，其中之一就是愤世嫉俗的敌意。……在愤世嫉俗敌意测量中得分高的人往往更容易患心脏病、代谢疾病，并且常常更年轻就去世。他们的端粒也更短。
定位线索：题干“What have scientists learned about cynical hostility”→答案句取自第3段“Scientists have learned that several thought patterns appear to be unhealthy for telomeres, and one of them is cynical hostility”和“They also have shorter telomeres”；文中“unhealthy for telomeres”和“shorter telomeres”对应选项B“produce an adverse effect on telomeres”。
解析：题干问科学家对愤世嫉俗敌意有何了解，答案句明确指出这种思维模式对端粒不健康，且具有高敌意的人端粒更短，即对端粒产生不利影响，对应选项B。选项A“导致对抗性思维模式”因果倒置，文中说愤世嫉俗敌意本身就是一种思维模式，而非导致其他思维模式；选项C“导致人们频繁发脾气”是文中对愤世嫉俗敌意的定义之一（高愤怒），但题干问的是科学家的发现，且这不是主要结论；选项D“在排队人群中激起 agitation”是文中举例的具体表现，不是科学家的主要发现，以偏概全。
50. What do we learn from the last paragraph about the process of aging?
- A. It may vary from individual to individual.
- B. It challenges scientists to explore further.
- C. It depends on one's genetic code.
- D. It may be controlled to a degree.
答案：D
答案句：What this means: aging is a dynamic process that could possibly be accelerated or slowed-and, in some aspects, even reversed.
参考译文：这意味着：衰老是一个动态过程，可能被加速或减缓——在某些方面，甚至可以被逆转。
定位线索：题干“What do we learn from the last paragraph about the process of aging”→答案句取自末段“aging is a dynamic process that could possibly be accelerated or slowed”；文中“could possibly be accelerated or slowed”对应选项D“be controlled to a degree”。
解析：题干问从最后一段我们能了解到衰老过程的什么，答案句明确指出衰老是一个动态过程，可能被加速或减缓，甚至在某些方面被逆转，即在一定程度上可以被控制，对应选项D。选项A“因人而异”是第1段内容，不是末段重点；选项B“挑战科学家进一步探索”无中生有，末段未提及；选项C“取决于基因密码”与末段内容相反，末段说端粒不只是执行基因密码的指令，还受生活方式等因素影响。