单项选择题 Exercising Your Memory 1 Aging does not mean a dramatic decline in memory power, unless you help ithappen by letting your mind go.2 That's not to say that memory doesn't change throughout life. Researchers dividememory into categories based on the length of time when memories are stored. Onesystem divides it up as short-term (less than one minute; remembering a telephonenumber while you dial, for instance), long-term (over a period of years) and verylong-term memory (over a lifetime).3 Short-term memory isn't mastered until about age 7, but after that you never lose it. Long-term memory, however, involves more effort and skill and changes more through life. It's not until the early teens (十几岁) that most people develop a mature long-term memory.4 First, we must get information into our heads through learning. Learning strategies can get rusty (生锈的) without constant use. High school and college students, who are forced to repeatedly exercise their long-term memory abilities (at least long-term enough to get them through a final exam), usually do well on memory tests. The longer you stay in school, the more chance you get to polish your learning, skills. It's no wonder that more highly educated people have more effective memory skills throughout life.5 Although older people in general learn somewhat more slowly than they did-whenyounger, a dramatic difference exists between those who stay intellectually active --reading, discussing, taking classes, thinking -- and those who do not. Giving the brain a daily workout (锻炼) is just as important as exercising your muscles. Brainwork keeps your learning strategies in shape, and this helps your memory to function at full capacity.6 The next part of a healthy long-term memory is retention (记忆力), the ability to store what you have learned. Memory researchers still do not know whether memories are lost--whether they still exist in the brain but our mental searching cannot turn them up, or have disappeared entirely as our brain ages.7 The third necessity for memory is recall, the ability to bring to mind the memories we have stored. Again, while aging has widely different effects on the recall abilities of different people, research indicates that the older we get, the longer it takes to recall facts. But slower recall is still recall. In fact, aging does not seem to have any effect on forgetting at all, which takes place at the same rate in younger and older people. 第 23 题 Paragraph 3＿＿＿＿＿＿＿

单项选择题 第三篇 Is the News Believable? Unless you have gone through the experience, yourself or watched a loved one's struggle, you really have no idea just how desperate cancer can make you. You pray, you rage, you bargain with God, but most of all you clutch at any hope, no matter how remote, of a second chance at life.For a few excited days last week, however, it seemed as if the whole world was a cancer patient and that all humankind had been granted a reprieve (痛苦减轻). Triggered by a front-page medical news story in the usually reserved New York Times, all anybody was talking about-- on the radio, on television, on the Internet, in phone calls to friends and relatives -- was the report that a combination of two new drugs could, as the Times. put it, 'cure cancer in two years.'In a matter of hours patients had jammed their doctors' phone lines begging for a chance to test the miracle cancer cure. Cancer scientists raced to the phones to make sure everyone knew about their research too, generating a new round of headlines.The time certainly seemed ripe for a breakthrough in cancer. Only last monthscientists at the National Cancer Institute announced that they were halting a clinical trial of a drug called tamoxifen (他莫昔芬) － and offering it to patients getting the placebo (安慰剂) --- because it had proved so effective at preventing breast cancer (although it also seemed to increase the risk of uterine (子宫的) cancer). Two weeks later came the New York Times' report that two new drugs can shrink tumors of every variety without any side effects whatsoever.It all seemed too good to be true, and of course it was. There are no miracle cancer drugs, at least not yet. At this stage all the drug manufacturer can offer is some very interesting molecules, and the only cancers they have cured so far have been in mice. By the middle of last week, even the TV talk-show hosts who talked most about the news had learned what every scientist already knew: that curing a disease in lab animals is not the same as doing it in humans. 'The history of cancer research has been a history of curing cancer in the mouse,' Dr. Richard Klausner, head of the National Cancer Institute, told the Los Angeles Times. 'We have cured mice of cancer for decades － and it simply didn't work in people.' 第 41 题 According to the passage, a person suffering from cancer willA． give up any hope.B．pray for the health of his loved ones.C． go out of his way to help others.D． seize every chance of survival.

单项选择题 tumorC． thingD． group