47. What do we learn about organic food from science?
- A. Whether it is any better remains uncertain.
- B. Whether it is healthier is under consideration.
- C. Whether it is more nutritious than conventional food is arguable.
- D. Whether it is going to replace conventional food is still unclear.
答案：A
答案句：Science won't give a clear-cut answer to the question of whether organic food is “better.”There are often trade-offs(权衡)and answers become less definitive depending on the product under consideration.
参考译文：科学不会对有机食品是否“更好”给出明确答案。通常存在权衡，答案会因所考虑的产品而变得不那么确定。
定位线索：题干“from science”→答案句取自第3段“Science won't give a clear-cut answer...”；文中“won't give a clear-cut answer”对应选项A“remains uncertain”；文中“answers become less definitive”进一步支持A。
解析：答案句明确指出科学对有机食品是否更好没有明确答案，对应A项“是否更好仍不确定”。B项“是否更健康在考虑中”偷换概念，文中未提健康；C项“是否更有营养有争议”与后文“equally nutritious”矛盾；D项“是否取代传统食品”无中生有。
48. What does the passage say about organic and non-organic products as far as food safety is concerned?
- A. Their difference is the conventions used to test them.
- B. They differ in how much pesticide remains on them.
- C. One relies on pesticides whereas the other does not.
- D. There is no substantial difference between the two.
答案：D
答案句：There is also no big difference between organic and non-organic products from a food-safety perspective.
参考译文：从食品安全的角度来看，有机产品和非有机产品之间也没有大的区别。
定位线索：题干“food safety”→答案句取自第5段“from a food-safety perspective”；文中“no big difference”对应选项D“no substantial difference”。
解析：答案句直接说明从食品安全角度看有机和非有机产品没有大区别，对应D项“两者没有实质性差异”。A项“测试惯例的差异”无中生有；B项“残留农药量不同”与文中“little if any pesticide remains”矛盾；C项“一个用农药另一个不用”与文中“Even organic growers use pesticides”矛盾。
49. What does the author say about organic farming?
- A. It may be blamed for the shrinking bee populations in the world.
- B. It minimizes the use of controversial pesticides in its operations.
- C. It may impact the environment less than conventional farming.
- D. It contaminates groundwater as much as conventional farming.
答案：C
答案句：On the whole, organic agriculture may have a smaller environmental footprint. That's mostly because the risk of groundwater contamination from organic farming is lower.
参考译文：总的来说，有机农业可能有更小的环境足迹。这主要是因为有机农业造成地下水污染的风险更低。
定位线索：题干“organic farming”→答案句取自第7段“organic agriculture may have a smaller environmental footprint”；文中“smaller environmental footprint”对应选项C“impact the environment less”；文中“risk of groundwater contamination...is lower”对应C项“less than conventional farming”。
解析：答案句明确指出有机农业环境足迹更小，地下水污染风险更低，对应C项“对环境的影响可能小于传统农业”。A项“可能被归咎于蜜蜂减少”与文中“organic farmers never used neonics”矛盾；B项“最小化使用争议农药”偷换概念，文中说有机农民不使用新烟碱类农药，但用其他农药；D项“污染地下水与传统农业一样多”与文中“risk...is lower”矛盾。