The milk of many mammals contains cannabinoids, substances that areknown to stimulate certain receptors in the brain. To investigate the functionof cannabinoids, researchers injected newborn mice with a chemical that isknown to block cannabinoides from reaching their receptors in the brain. Theinjected 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 notnormally ingest any substance other than their mothers’ milk.
B. Cannabinoids are the onlysubstances in mammals’ milk that stimulate the appetite.
C. The mothers of newbornmice do not normally make any effort to encourage their babies to feed.
D. The milk of mammals wouldbe less nutritious if it did not contain cannabinoids.
E. The chemical that blockscannabinoids from stimulating their brain receptors does not independentlyinhibit the appetite.
答案是E，我选了C，有没有NN能够帮我讲讲这题的思路？55555555 | 
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发表于 2010-8-29 23:27:06
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发表于 2010-8-30 07:22:03
