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题库 / Prep2007E2-CR-43
Half of the subjects in an experiment—the experimental group—consumed large quantities of a popular artificial sweetener. Afterward, this group showed lower cognitive abilities than did the other half of the subjects—the control group—who did not consume the sweetener. The detrimental effects were attributed to an amino acid that is one of the sweetener's principal constituents.
Which of the following, if true, would best support the conclusion that some ingredient of the sweetener was responsible for the experimental results?
Most consumers of the sweetener do not consume as much of it as the experimental group members did.
The amino acid referred to in the conclusion is a component of all proteins, some of which must be consumed for adequate nutrition.
The quantity of the sweetener consumed by individuals in the experimental group is considered safe by federal food regulators.
The two groups of subjects were evenly matched with regard to cognitive abilities prior to the experiment.
A second experiment in which subjects consumed large quantities of the sweetener lacked a control group of subjects who were not given the sweetener.
P:实验组在吃了sweetener以后认知能力比没有吃的控制组要低。-> C:amino acid造成了这种差异
choice d, 两组人员在实验之前的认知能力相当
果因论证。
弱加强：无他因。
实验组吃大量流行人工甜味剂，之后此组认知能力比没吃甜味剂的控制组更低。关键因素是甜味剂里的氨基酸。
增强题
(A) 甜味剂消费者和实验组比；无关比较，排
(B) 谈氨基酸的情况；无关，排
(C) 实验组吃的甜味剂数量被认为是安全的；无关，排
(D) 两组在实验前的认知能力相当；排除认知不同的影响，排他增强，正确
(E) 第二个实验只有实验组；第二个实验，跳出范围，排
D选项，表明实验无偏，即排除原来一组人本来就比另一组人的cognitive abilities更低下，如果有这种情况发生，那么无论你吃不吃糖，都无法改变实验结果
這道題最大的特色是沒有解答為什麼出現不同。
方案類。
加強，1.可以解釋原因 2.沒有削弱（沒有反例，沒有干擾因素）
E選項看得不太懂，應該是第二次實驗無關。