Plant scientists have been able to genetically engineer vegetable seedsto produce crops that are highly resistant to insect damage. Althoughthese seeds currently cost more than conventional seeds, their cost is likely to decline. Moreover, farmers planting them can use far less pesticide, and most consumers prefer vegetables grown with less pesticide,therefore, for crops for which these seeds can be developed, their use is likely to become the norm.
Which of the following would be most useful to know in evaluating theargument above?
A.Whether plant scientists have developed insect-resistant seedsfor every crop that is currently grown commercially
B.Whether farmers typically use agricultural pesticides in largeramounts than is necessary to prevent crop damage.
C.Whether plants grown from the new genetically engineered seedscan be kept completely free of insect damage.
D.Whether seeds genetically engineered to produce insect-resistantcrops generate significantly lower per acre crop yields than docurrently used seeds.
E.Whether most varieties of crops currently grown commercially havegreater natural resistance to insect damage than did similar varieties in the past.
选D，不太明白题目里的 become norm 成为标准是什么意思？成为什么的标准？而且为什么不选e呢？是否现在的比过去的更可以抵抗昆虫了，如果yes那就没必要用科学家的种子了，如果否 则需要科学家的种子啊~~~~ | 
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发表于 2010-5-7 15:41:34
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