The milk of many mammals contains cannabinoids, substances that are known to stimulate certain recep...

题目信息

The milk of many mammals contains cannabinoids, substances that are known to stimulate certain receptors in the brain. To investigate the function of cannabinoids, researchers injected newborn mice with a chemical that is known to block cannabinoids from reaching their receptors in the brain. The injected mice showed far less interest in feeding than normal newborn mice do. Therefore, cannabinoids probably function to stimulate the appetite.

Which of the following is an assumption on which the argument depends?

A:Newborn mice do not normally ingest any substance other than their mothers' milk.

B:Cannabinoids are the only substances in mammals' milk that stimulate the appetite.

C:The mothers of newborn mice do not normally make any effort to encourage their babies to feed.

D:The milk of mammals would be less nutritious if it did not contain cannabinoids.

E:The chemical that blocks cannabinoids from stimulating their brain receptors does not independently inhibit the appetite.

参考答案及共享解析

共享解析来源为网络权威资源、GMAT高分考生等；如有疑问，欢迎在评论区提问与讨论

正确答案： E:The chemical that blocks cannabinoids from stimulating their brain receptors does not independently inhibit the appetite.

milk含有can，can可以作用于大脑，具体作用是什么有待研究。研究者做实验，加入一种可以抑制Can的chemical之后发现实验对象的胃口下降。结论：Can的作用是促进appetite。也就是说Can和appetite正相关。 assumption: 就是要找到取非之后可以weaken原结论的，即证明C和apprtite无因果相关性。取非E选项，注入的化学物质会单独影响食欲，说明实验对象无胃口不是缺少can物质引起的，而是注入的化学物质引起的，这样就找到了第三方因素，取消了原结论的因果相关性。

笔记