GWD24-29我怎么觉得没有正确答案哩？

3bao

谢谢

gtong

這題可以用更簡單的方式看來把B刪除:
Cost of genetically engineer vegetable seeds=pesticide+others
Cost of conventional seeds=pesticide+others

B):Whether farmers typically use agricultural pesticides in larger amounts than is necessary to prevent crop damage.

B選項適用於基因種子和傳統種子，所以兩個pesticide同時增加減少並不會影響兩者之間的cost差距,所以B是無關選項

lemonsong

赞同……
其实B只能evaluate一部分，如果non-resistant的实际只需要更少的农药，可能也不会被淘汰，但我们无法确定结果。
而D中significantly，更好。

C是無關, 因為第一句:
Plant scientists have been able to genetically engineer vegetable seeds  to produce crops that are highly resistant to insect damage.
告訴我們, author巳知道那generically engineered vegetable seeds不能completely free of insect damage.
文裏有幾個keywords: cost, less pesticide, resistant to insect damage
B跟less pesticide有關
D跟cost有關
E跟resistant to insect damage有關, 可是author寫時候是"現在時", 所以過去是怎樣應該巳被考慮/無關..

if B is true, less use of pesticide is possible=>no increase in cost, keep the current level of resistance to insect damage=>Generically engineered vegetable seeds are not necessary=>weaken
if B is false, generically engineered vegetable seeds might be widely used because they can lower the use of pesticide, cost will not be a problem in a long run (because "their cost is likely to decline"), and they offer high resistance to insect damage=>strength

if D is true, cost will go up=>farmers might decide NOT to use generically engineered vegetable seeds.  Although "most consumers prefer vegetables grown with less pesticide", farmers are the ultimate decision makers (well unless all customers are not going to eat vegetables)=>weaken
if E is false, cost will not be a problem in a long run (because "their cost is likely to decline")=>farmers might use generically engineered vegetable seeds for less pesticide and high resistance to insect damage.=>strength

看上去好像B/D都有理...

-- by 会员 AlienX (2009/1/2 3:38:00)