10. Rhizobium bacteria living in the roots of bean plants or other legumes produce fixed nitrogen which is one of the essential plant nutrients and which for non-legume crops, such as wheat normally must be supplied by applications of nitrogen-based fertilizer. So if biotechnology succeeds in producing wheat strains whose roots will play host to Rhizobium bacteria. The need for artificial fertilizers will be reduced. The argument above makes which one of the following assumptions? (A) Biotechnology should be directed toward producing plants that do not require artificial fertilizer. (B) Fixed nitrogen is currently the only soil nutrient that must be supplied by artificial fertilizer for growing wheat crops. (C) There are no naturally occurring strains of wheat or other grasses that have Rhizobium bacteria living in their roots. (D) Legumes are currently the only crops that produce their own supply of fixed nitrogen. (E) Rhizobium bacteria living in the roots of wheat would produce fixed nitrogen. answer:E my choice:B why not be right for B?
If NOT B, the conclusion will not be weakened, because the conclusion of the passage is that if biotechnology succeeds in producing wheat strains whose roots will play host to Rhizobium bacteria,the need for artificial fertilizers will be reduced, so the focus is nitrogen-based fertilizer, there is no any relationship with other soil nutrients.
我觉得原文是说会减少，如果对e取非，即Rhizobium bacteria living in the roots of wheat would not produce fixed nitrogen,比如制造varied nitrogen,也可以减少人工化肥啊，只是量的区别而已。--MM把原题的条件都改了阿，已经说了这些原来没有固氮菌的作物 such as wheat normally must be supplied by applications of nitrogen-based fertilizer
求助
同时，对B取非，(B) Fixed nitrogen is NOT currently the only soil nutrient that must be supplied by artificial fertilizer for growing wheat crops. 还有其他营养也需要人工化肥来供给，那么化肥的用量还是有可能减少（有了固氮菌，氮可以少用），丝毫不影响原题的结论
which for non-legume crops, such as wheat normally must be supplied by applications of nitrogen-based fertilizer 这个which是指fixed nitrogen，而非nitrogen,E肯定没问题了。
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发表于 2003-9-4 10:51:00
