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题库 / OG2019-CR-554
Which of the following most logically completes the passage?
Leptin, a protein occurring naturally in the blood, appears to regulate how much fat the body carries by speeding up the metabolism and decreasing the appetite when the body has too much fat. Mice that do not naturally produce leptin have more fat than other mice, but lose fat rapidly when they are given leptin injections. Unfortunately, however,leptin cannot be used as a dietary supplement to control fat, since __________.
the digestive system breaks down proteins before they can enter the bloodstream
there are pharmaceuticals already available that can contribute to weight loss by speeding up the metabolism
people with unusually low levels of leptin in their blood tend to have a high percentage of body fat
the mice that do not naturally produce leptin were from a specially bred strain of mice
mice whose bodies did produce leptin also lost some of their body fat when given leptin injections
情景：Leptin是一种在血液里能够调节脂肪的蛋白质（当脂肪多的时候就加速新陈代谢并且减少胃口）。无法自然产生Leptin的老鼠有更多的脂肪，但当他们被注射Leptin的时候就疯狂减脂。然而，我们并不能直接通过饮食摄入leptin来控制脂肪，因为_______。
推理：这种现象解释型考题，题目中正常的逻辑顺序是：
因为Leptin可以调节脂肪，
所以我们可以通过直接摄入来控制脂肪。
我们要对这一逻辑链进行削弱。
选项分析：
A选项：正确。在蛋白质进入血液之前，消化系统会将其分解：解释了为什么不能通过饮食摄入leptin的方式减脂，因为leptin在起作用之前就没了，自然无法达到预期效果。
B选项：已经有可以通过加速新陈代谢减肥的药物了：有没有别的药物和leptin能不能发挥作用无关。
C选项：有低leptin的人通常脂肪较多：重复题干中的前提是无法削弱的。
D选项：没有leptin的老鼠来自一个特殊培育的老鼠品种：与我们为什么不能直接摄入leptin无关。
E选项：有leptin的老鼠在被注入leptin的时候也会失去一些脂肪：与我们为什么不能直接摄入leptin无关。
1.提炼P&C
P（因）：小老鼠注射leptin后减肥很快
C（果）：leptin can be used as a dietary supplement to control fat
2.判断推理方式：因果推理
3.评估预判：
CQ1：干扰因素：，反驳结论
CQ2：因果联系：
4.将选项和CQ进行匹配
A选项：CQ1
there are pharmaceuticals already available that can contribute to weight loss by speeding up the metabolism
weight loss复合名词，重量丢失，减肥；contribute to sth，增进，捐助，没有contribute to do sth