prep2-4

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，D怎么不好呢？

我觉得这题中心在说　距离小使得没株的产量减少，但实际上正亩产量增加，让解释原因，

我觉得d　不能解释产量增加，如果总的株数增加一倍，但每株的产量减少超过一倍，那正亩总产量还是减少

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 成本降低了自然利润上升
(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 无关
(C) with the larger number of plants growing per acre, more fertilizer will be required 削弱
(D) with the spacing between rows cut by half, the number of plants grown per acre will almost double 不能作为conclusion不能说明利润上升, 只能说明种的玉米多了
(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 无关

收成降低利润却可以翻倍, 解释原因.

(D) with the spacing between rows cut by half, the number of plants grown per acre will almost double
            plants的数量double了，但是per plant的产量减少(不知是少过一半或少不到一半)，所以不确定总产量是增加或减少。

（A）说可以减少cost，我们认为可能会带来利润，但是减少的cost也不一定可以抵消产量减少带来的损失。

（D）当然也不对，因为单位产量和数量的两者乘积不一定大于本来的产量

我觉得这个题目应该这样理解：

题目中有个double their profits，而我们看（D）中即使种的数量double了，但是因为单位产量的减少，因此每亩产量不可能double，也就是说无论如何无法double the profits。

因此两者比较（A）更靠近正确答案

问题大大的，d每株的产量减少，每亩种的株数增加，无法得出最后每亩产量增加或减少的结论，也无从得知最终利润的得失。但是a 除草成本下降也不能得出每亩利润增加的结论呀，除草成本下降可能使每单位土地上的种植成本下降，但是如果单位土地上玉米的产量减少，除草成本摊到每个玉米上同样可能增加，导致利润降低。即使单位土地上玉米产量增加，相应的除草成本降低，提高利润，但是因为每亩的产量不得而知，不能推出每亩的利润增加，请NN指教。