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  3. Mycorrhizal fungi infect more plants than do any other fungi and are necessary for many plants to thrive, but they have escaped

Mycorrhizal fungi infect more plants than do any other fungi and are necessary for many plants to thrive, but they have escaped

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问题     Mycorrhizal fungi infect more plants than do any other fungi and are necessary for many plants to thrive, but they have escaped widespread investigation until recently for two reasons. First, the symbiotic association is so well-balanced that the roots of host plants show no damage even when densely infected. Second, the fungi cannot as yet be cultivated in the absence of a living mot. Despite these difficulties, there has been important new work that suggests that this symbiotic association can be harnessed to achieve more economical use of costly super phosphate fertilizer and to permit better exploitation of cheaper, less soluble rock phosphate, Mycorrhizal benefits are not limited to improved phosphate uptake in host plants. In legumes, mycorrhizal inoculation has increased nitrogen fixation beyond levels achieved by adding phosphate fertilizer alone. Certain symbiotic associations also increase the host plant’s resistance to harmful root fungi. Whether this resistance results from exclusion of harmful fungi through competition for sites, from metabolic change involving antibiotic production, or from increased vigor is undetermined.
The level of information in the passage above is suited to the needs of all of the following people except______.
选项 A、an official of a research foundation who identifies research projects for potential funding
B、a state official whose position requires her to alert farmers about possible innovations in farming
C、a researcher whose job is to identify potentially profitable areas for research and product development
D、a botanist conducting experiments to determine the relationship between degree of mycorrhizal infection and expected uptake of phosphate
答案B
解析 本题中，A、C、D三项正确，文中用了很多生物学术语，说明本文很专业化，所以它应该是写给生物学领域的专业人士看的。官员并不需要具备如此深的专业知识去指导农民，因此答案为B。
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