题目

下图所示变化属于化学变化的是 A．瓷碗破碎      B．葡萄酿酒       C．湿衣晾干       D．灯泡通电发光 答案：BGeorge Spilich at Washington College in Chestertown, Maryland, decided to find out whether, as many smokers say, smoking helps them to “think and fix their attention on (集中精力于)their work”. Spilich put young non－smokers, active smokers and smokers deprived(被剥夺)of cigarettes through a series of tests. In the first test, each subject sat before a computer screen and pressed a key as soon as he or she recognized a certain letter among a grouping of 96. In this simple test, smokers, deprived smokers and non－smokers performed equally well. The next test was more difficult, requiring all to scan(扫描) groups of 20 letters and find the one of the letters changed into a different one. Non－smokers were faster, but under the stimulation(刺激)of nicotine, active smokers were faster than deprived smokers. In the third test of short－term memory, non－smokers made the fewest mistakes, but deprived smokers made fewer mistakes than active smokers. The fourth test required people to read a passage, then answer questions about it. Non－smokers remembered 19 percent more of the most important information than active smokers, and deprived smokers did better than those who had smoked a cigarette just before testing. Active smokers were likely not only to have poorer memories but also had trouble separating important information from unimportant details. “As our tests became more difficult，” says Spilich, “non－smokers performed better than smokers by far.” he says, “Smokers might perform adequately(准确)at many jobs until they got very difficult. A smoking airline pilot could fly adequately if no problems arose, but if something went wrong, smoking might damage his mental capacity(思维能力)．” 1. Smokers usually think that smoking ________. A. helps them to be less nervous B. helps them to do better work C. helps them to think and act quickly D. does some good to their health 2. George Spilich's experiment was organized in such a way as to ________. A. force the subjects to separate major information from minor details B. check the effectiveness of nicotine on smokers C. put the subjects through increasing difficult test D. make a written and formal record of the answers of the subjects 3. Which fact does this passage lead us to believe? A. Active smokers generally performed better than deprived smokers. B. Active smokers answered more quickly than the other subjects. C. Deprived smokers gave the slowest answers to the various tasks. D. Non－smokers were not better than other subjects in performing simple tasks. 4. We can infer from the last paragraph that ________. A. smokers should not expect to become airline pilots B. smokers may prove unequal to dealing with emergency (紧急) cases C. no airline pilots smoke during flights D. smoking in emergency cases causes mental illness