Read the following passage and choose the most likely answer to each of the following questions.
Researchers have established that when people are mentally engaged (投入的), biochemical (生物化学的) changes occur in the brain that allow it to act more effectively in cognitively (认知的) areas such as attention and memory. This is true regardless of age. People will be alert 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 the brain that they are putting the theory to work in their own lives. "The idea is not necessarily to learn to memorize enormous amounts of information," says James Fozard, associate director of the National Institute on Aging. "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 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's health and size."
What is the passage mainly about?
A、
How biochemical changes occur in the human brain?
B、
Why people should keep active not only physically but also mentally?
C、
How intellectual activities influence brain-cell health?
D、
Why people should receive special mental training as they age?
【正确答案】：B
【题目解析】：
本文一直强调保持精神活跃的重要性，并在最后一段中讲到：科恩说，我们经常被建议随着年龄增长保持身体活跃，但老年人也需要保持精神活跃。这样做的人更有可能保持他们的智力，通常更快乐，调整更好。“关键是，你需要同时做到这两个。”科恩说，“智力活动实际上影响了脑细胞的健康和大小。”故B项正确，即为什么人们不仅要保持身体上的活跃，还要保持精神上的活跃？
。