51. What has been a standard piece of dietary advice for decades?
- A. People should cultivate a healthy eating habit.
- B. People should have a well-balanced diet.
- C. People should diversify what they eat.
- D. People should limit calorie intake to avoid obesity.
答案：C
答案句：The suggestion that people should aim for dietary diversity by trying to eat a variety of foods has been a basic public health recommendation for decades in the United States and elsewhere.
参考译文：人们应该通过尝试吃多种食物来实现饮食多样化的建议，几十年来在美国和其他地方一直是一项基本的公共卫生建议。
定位线索：题干“standard piece of dietary advice for decades”→答案句“basic public health recommendation for decades”；文中“aim for dietary diversity by trying to eat a variety of foods”对应选项C“diversify what they eat”。
解析：题干问几十年来标准的饮食建议是什么，答案句直接指出“aim for dietary diversity by trying to eat a variety of foods”是基本的公共卫生建议，即多样化饮食，对应选项C。选项A“培养健康饮食习惯”范围过大，选项B“均衡饮食”未提及，选项D“限制卡路里”是后文新研究的观点，答非所问。
52. What did the new research by the American Heart Association find?
- A. People seeking dietary diversity tend to eat more.
- B. Big eaters are more likely to become overweight.
- C. Dietary diversity is positively related to good health.
- D. Unhealthy food makes people gain weight more easily.
答案：A
答案句：Researchers reviewed all the evidence published related to dietary diversity and saw a correlation between dietary diversity and a greater intake of both healthy and unhealthy foods. This had implications for obesity, as researchers found a greater prevalence of obesity amongst people with a greater dietary diversity.
参考译文：研究人员回顾了所有已发表的与饮食多样性相关的证据，发现饮食多样性与摄入更多健康和不健康食物之间存在相关性。这对肥胖有影响，因为研究人员发现饮食多样性更高的人群中肥胖患病率更高。
定位线索：题干“new research by the American Heart Association”→答案句“Researchers reviewed all the evidence”；文中“greater intake of both healthy and unhealthy foods”对应选项A“tend to eat more”；文中“greater prevalence of obesity”对应选项B“more likely to become overweight”。
解析：题干问新研究发现什么，答案句指出饮食多样性与摄入更多食物相关，且肥胖患病率更高，对应选项A和B。但选项A直接对应“greater intake”，而选项B是“肥胖患病率更高”的转述，两者都正确，但题目为单选，需注意选项A更直接。选项C与原文“greater intake of unhealthy foods”矛盾，选项D“不健康食物”未直接提及，偷换概念。
54. What did Dr. Rao find after 20 years of research on obesity?
- A. Dietary diversity promotes healthy body weight.
- B. Eating patterns and weight gain go hand in hand.
- C. Diversified food intake may not contribute to health.
- D. There is no clear definition of optimal eating patterns.
答案：C
答案句：Dr. Rao, one of the study authors, noted that, after 20 years of experience in the field of obesity, he has observed that people who have a regimented lifestyle and diet tend to be thinner and healthier than people with a wide variety of consumption.
参考译文：该研究的作者之一Rao博士指出，在肥胖领域有20年经验后，他观察到生活方式和饮食有规律的人往往比饮食多样化的人更瘦、更健康。
定位线索：题干“Dr. Rao find after 20 years”→答案句“after 20 years of experience”；文中“people with a wide variety of consumption”对应选项C“Diversified food intake”；文中“tend to be thinner and healthier”对应选项C“may not contribute to health”。
解析：题干问Rao博士20年研究后的发现，答案句指出饮食多样化的人不如饮食规律的人健康，即多样化饮食可能不利于健康，对应选项C。选项A与原文矛盾，选项B“饮食模式和体重增加”未直接提及，选项D“最佳饮食模式定义”无中生有。