Researchers took a group of teenagers who had never smoked and for one year tracked whether they took up smoking and how their mental health changed. Those who began smoking within a month of the study’s start were four times as likely to be depressed at the study’s end than those who did not begin smoking. Since nicotine in cigarettes changes brain chemistry, perhaps thereby affecting mood, it is likely that smoking contributes to depression in teenagers. Which of the following, if true, most strengthens the argument?
Participants who were depressed at the study’s start were no more likely to be smokers at the study’s end than those who were not depressed.
Participants who began smoking within a month of the study’s start were no more likely than those who began midway through to have quit smoking by the study’s end.
Few, if any, of the participants in the study were friends or relatives of other participants.
Some participants entered and emerged from a period of depression within the year of the study.
The researchers did not track use of alcohol by the teenagers.
A。Participants who were depressed at the study’s start were no more likely to be smokers at the study’s end than those who were not depressed。A如何体现兄弟以上这句话》在研究开始的时候，那么参与者已经是depress了，他们比那么不depress的人更少可能会在研究结束后成为吸烟者。不明白的是，A已经说了，相对来说，他们（depress的人）最后不怎么可能成为吸烟者，如果这样的话，怎么说明之前他们是抽烟导致压抑？
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发表于 2005-8-10 08:20:00
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