Researchers have established that when people are mentally engaged, biochemical changes occur in the brain that allow it to act more effectively in cognitive(认知的) areas such as attention and memory. This is true regardless of age.People will be alert(警觉的)and receptive if they are faced with information that gets them to think about things they are interested in. And someone with a history of doing more rather than less will go into old age more cognitively sound than someone who has not had an active mind.Many experts are so convinced of the benefits of challenging in the brain that they are putting the theory to work in their own lives. “The idea is not necessarily to learn to memorize large amounts of information,” says James Fozard, associate director of the National Institute of Ageing. “Most of us don’t need that kind of skill. Such specific training is of less interest than being able to maintain mental alertness.” Fozard and others say they challenge their brains with different mental skills, both because they enjoy them and because they are sure that their range of activities will help the way their brains work.Gene Cohen, acting director of the same institute, suggests that people in their old age should engage in mental and physical activities individually as well as in groups. Cohen says that we are frequently advised to keep physically active as we age, but older people need to keep mentally active as well. Those who do are more likely to maintain their intellectual abilities and to be generally happier and better adjusted. “The point is, you need to do both,” Cohen says. Intellectual activity actually influences brain-cell health and size.(1)What is the passage mainly about?()A. Special mental training for old people.B. Biochemical changes in the human brain.C. The influence of intellectual activities on brain-cell size.D. The importance of mental activities in the efficiency of the brain.(2)A person who is said to be cognitively healthy should ().A. be alert and receptive in mind B. who are highly intelligentC. be good at doing group work D. remember large quantities of information(3) The findings of James and other scientists in their work ().A. remain a theory to be further proved B. have been challenged by many other expertsC. are practiced by the researchers themselves D. have been generally accepted(4)According to Fozard's argument, people can make their brains work more efficiently by ().A. constantly doing memory work B. making frequent adjustmentsC. going through specific training D. taking part in various mental activities(5) Which of the following statements would Cohen most probably support?()A. Older people should keep mentally active by challenging their brains.B. No matter whether it is done in group or alone, mental activity is always good for brain-cell health.C. Physical strength is more important to older people than mental health.D. People who engage in more mental activities but less physical ones are always happier.