题目

用单调性的定义证明：函数在区间上是减函数. 答案：证明：设，则 ＝在上是减函数.For most caffeine(咖啡因)consumers, its main benefit is that it helps you get more done. This is what makes it unusual, says Stephen Braun, author of Buzz: The Science and Lore of Alcohol and Caffeine.“Its appeal is that it helps us earn more money,” he adds. “What makes it different from other drugs is that it’s used as a productivity tool –– not for pleasure.” Many of history’s creative minds have also been connected with a large amount of caffeine consumption (消耗).According to one biographer, the French novelist and playwright Balzac drank as many as 50 cups of coffee a day. “Were it not for coffee one could not write, which is to say one could not live,” he once insisted.For seven years, the film-maker David Lynch ate at the same Los Angeles diner every day, drinking up to seven sweetened cups of coffee “with lots of sugar” in one sitting, which he said would guarantee that “lots of ideas” arrived.Ludwig van Beethoven was said to have painstakingly counted out exactly 60 coffee beans per cup when he brewed(煮)coffee.Perhaps recent tales of caffeine excess (过量) featured the singer Robbie Williams, who reportedly consumed 36 cups of black coffee and 20 cans of Red Bull a day.It is the routine task itself, as much as the stimulating(刺激的)effects of caffeine, that makes the process so important, says Mason Currey, author of Daily Rituals: How Artists Work. “A lot of artists use the process of making coffee as a gateway to the creative process,” he adds. “You need to get into the right mindset to do that sort of work, and the preparation process provides a focus.”One problem with attempting to control caffeine, says Braun, is that it affects everyone differently –– it is impossible to work out a “safe” limit that works for everyone. “Eventually, you have to become your own scientist –– there isn’t an alternative to careful self-experimentation,” he says.1.The examples of some famous people are given to show that _______.A. most artists like drinking coffee B. drinking coffee helps artists make more moneyC. there’s a link between drinking coffee and creating ideas D. drinking coffee makes artists become more successful2.What leads to the artists’ creative process according to Mason Currey?A. Being lost in thought. B. Drinking the coffee. C. Brewing the coffee. D. Getting a good mindset.3.What does Braun advise us to do in the end?A. To drink less coffee. B. Never to limit caffeine use. C. To work out a safe level of caffeine use. D. Never to take more coffee than you need.