真题训练：
Which of the following most logically completes the argument below?
Davison River farmers are currently deciding between planting winter wheat this fall or spring wheat next spring. Winter wheat and spring wheat are usually about equally profitable. Because of new government restrictions on the use of Davison River water for irrigation, per acre yields for winter wheat, though not for spring wheat, would be much lower than average. Therefore, planting spring wheat will be more profitable than planting winter wheat, since .
(A) the smaller-than-average size of a winter wheat harvest this year would not be compensated for by higher winter wheat prices
(B) new crops of spring wheat must be planted earlier than the time at which standing crops of winter wheat are ready to be harvested
(C) the spring wheat that farmers in the Davison River region plant is well adapted to the soil of the region
(D) spring wheat has uses that are different from those of winter wheat
(E) planting spring wheat is more profitable than planting certain other crops, such as rye
分析：
原文：政府对灌溉用水的限制--冬小麦每英亩产量减小---冬小麦和春小麦的选择
问题：春小麦利润高的理由。
解题关键：原文谈钱，选项谈钱更有关。
选项：
A，冬小麦高价不能补偿冬小麦收获的减少;潜台词：冬小麦利润减少，小于春小麦。有关
B，春小麦的种植必须早于冬小麦的收割;种植时间，无关。
C，春小麦更适合土壤;无关。
D，春小麦的作用与冬小麦不同，无关。
E，种春小麦比其他庄稼利润高。无关比较。
答案：A。
真题训练2：
When there is less rainfall than normal, the water level of Australian rivers falls and the rivers flow more slowly. Because algae whose habitat is river water grow best in slow-moving water, the amount of algae per unit of water generally increases when there has been little rain. By contrast, however, following a period of extreme drought, algae levels are low even in very slow-moving river water.
Which of the following, if true, does most to explain the contrast described above?
(A) During periods of extreme drought, the populations of some of the species that feed on algae tend to fall.
(B) The more slowly water moves, the more conducive its temperature is to the growth of algae.
(C) When algae populations reach very high levels, conditions within the river can become toxic for some of the other species that normally live there.
(D) Australian rivers dry up completely for short intervals in periods of extreme drought.
(E) Except during periods of extreme drought, algae levels tend to be higher in rivers in which the flow has been controlled by damming than in rivers that flow freely.
原文：(雨量减少、流速较低、)严重干旱---algae 生长
问题：解释对比关系
解题关键：
选项：
A，干旱时，一些以algae为食的物种减少; 无意义概率，反向;
B，水流越慢，温度越适宜;无关;
C， algae 数量较高时，环境变得对其他物种有毒;无关
D，极度干旱时河水短期枯竭;潜台词，无法生长，有关
E， 除了干旱期，algae水平在水流受大坝控制的河里比在自由流动的河里较高;无关比较。
答案：选D。
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