求助prep2-4

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4. (24257-!-item-!-188;#058&001200)

Which of the following most logically completes the argument?

A new machine for harvesting corn will allow rows to be planted only fifteen inches apart, instead of the usual thirty inches.  Corn planted this closely will produce lower yields per plant.  Nevertheless, the new machine will allow corn growers to double their profits per acre because __________.

(A) with the closer spacing of the rows, the growing corn plants will quickly form a dense canopy of leaves, which will, by shading the ground, minimize the need for costly weed control and irrigation
(B) with the closer spacing of the rows, corn plants will be forced to grow taller because of increased competition for sunlight from neighboring corn plants
(C) with the larger number of plants growing per acre, more fertilizer will be required
(D) with the spacing between rows cut by half, the number of plants grown per acre will almost double
(E) with the closer spacing of the rows, the acreage on which corn is planted will be utilized much more intensively than it was before, requiring more frequent fallow years in which corn fields are left unplanted
答案是A
B为什么不对 

xfi883

原文大意：

    尽管——密集种植会降低产量

    但是——密集种植会提高利润

本题的三个关键点就是“密集种植”、“降低产量”和“提高利润”，看到主语“密集种植”，就能缩小答案选择范围；“降低产量”和“提高利润”就是进一步分析的关键。

答案A是说“密集种植可以通过降低成本达到提高利润的目的”，然而，B则是说“密集种植可以通过增加谷物高度，提高产量”所以错误。