Many health experts have recently suggested that plastic water bottles begin to break down over time, releasing a chemical called bisphenol A that can cause heightened risks of diabetes and cancer

题目

Many health experts have recently suggested that plastic water bottles begin to break down over time, releasing a chemical called bisphenol A that can cause heightened risks of diabetes and cancer. The experts found that this breakdown usually begins a year into the bottle’s use. Thus, people should stop using plastic water bottles after a year.

Which of the following, if true, would most weaken the conclusion above?

选项

The health experts found that among those using plastic bottles that had begun to release bisphenol A, the incidence of diabetes and cancer was no higher than among people who did not.

The health experts did not investigate the possible effects of other chemicals used in making plastic bottles, such as epoxy resins.

The health experts failed to determine why the breakdown of the plastic usually began only after the bottles had been in use for a year.

The health experts found that bottles stored in cool, safe places were as likely to break down and release bisphenol A as were bottles that were stored in hot places and subject to physical damage.

The health experts found that after eighteen months of use, greater length of the usage of a water bottle did not correlate with a higher level of bisphenol A being present.

解析

许多健康专家最近指出，塑料水瓶会随时间分解，释放一种名为双酚A（bisphenol A）的化学物质，这种物质会增加患糖尿病和癌症的风险。专家发现，这种分解通常在瓶子使用一年后开始。因此，人们应该在使用塑料水瓶一年后停止使用。 - **核心论点**：结论为“人们应该在使用塑料水瓶一年后停止使用”，论据为“塑料水瓶使用一年后开始分解，释放的双酚A会增加糖尿病和癌症风险”。 - **正确答案方向**：需找到能削弱“使用一年后停止使用”必要性的理由（如双酚A实际未增加患病风险、或有其他因素抵消风险等）。 - **选项A**：指出使用已释放双酚A的塑料瓶的人，其糖尿病和癌症发病率与不使用的人无差异。这直接削弱了“双酚A会增加患病风险”的论据——若双酚A未导致更高患病风险，“一年后停止使用”的必要性就不成立，当选。 - **选项B**：讨论“其他化学物质（如环氧树脂）的影响”，但结论关注的是“双酚A的影响”，与结论无关，无法削弱。 - **选项C**：分解开始的**原因**（为何一年后才分解）与“是否应一年后停止使用”无关，无法削弱结论。 - **选项D**：说明“不同储存条件下瓶子都可能分解”，这进一步支持“一年后瓶子会分解释放物质”的论据，反而可能**加强**“一年后停止使用”的结论，无法削弱。 - **选项E**：讨论“使用18个月后双酚A含量与使用时长的关系”，但结论关注的是“一年后是否停止使用”（一年后已开始分解）。18个月后的情况与“一年后是否需停止”无关，无法削弱。综上，正确答案为A。

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