阅读理解 Researchers have established that when people are mentally engaged, biochemical changes occur in the brain that allow it to act more effectively 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 Fazard, 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 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."

单选题 People who are cognitively healthy are those______.

A、 whose minds are alert and receptive
B、 who are highly intelligent
C、 who can remember large amounts of information
D、 who are good at recognizing different sounds

【正确答案】 A

【答案解析】细节题。本题询问的是什么样的人才能有较健全的认知能力。文章第二段的内容“People will be alert and receptive ... who has not had an active mind．”说明有健全的认知能力的人应该是选项A中所提到的头脑处于警觉和接受能力强的状态的人，故A为正确答案。

单选题 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 experts
C、 are practiced by the researchers themselves
D、 have been generally accepted

【正确答案】 C

【答案解析】推理题。本题询问James和其他科学家们的理论现在处于一种什么样的状态，文章第三段的第一句话“Many experts are so convinced of the benefits of challenging the brain that they are putting the theory to work in their own lives．”就说明James等人的这种研究结果还不曾被前人验证过，而科学家们自己也正把它付诸于实施。所以选项C为正确答案。同时，从这一段话中还可看出科学家们自己正把这一理论付诸于实施，该理论是否被广泛认可和接受，文章中并未提及，故选项D不是正确答案。选项A “James 等人的理论发现还需进一步证实”违背了文章第三段第一句话的内容，因为这句话中提到“Many experts are so convinced... that...”这就说明该理论已被许多科学家认可了，故选项A也不正确。而选项B“James等人的理论发现受到许多科学家的挑战”是本文所未涉及到的内容。

单选题 What is the passage mainly about?

A、 How biochemical changes occur in the human brain.
B、 Why people should receive special mental training as they age.
C、 How intellectual activities influence brain health.
D、 Why people should keep active not only physically but also mentally.

【正确答案】 D

【答案解析】主旨题。本题询问的是本文的主题思想。文章通篇讨论的是为什么在保持身体活力的同时，还必须保持大脑的活力，即告诉人们保持大脑健康的重要性。作者首先指出，人在用脑时，大脑会处于兴奋状态，这时大脑在诸如注意力和记忆力等属于认知领域的能力会有效地得以发挥。接着，作者谈及勤于动脑的重要性。勤于动脑的人即使到了老年，仍能保持心理健康。最后，作者指出，老年人不仅要坚持锻炼身体，而且要勤于动脑，只有这样才能保持身心健康，提高生活质量。尤其是在文章最后一段，作者通过Gene Cohen的话指出老年人应参加个人或集体的体力和脑力锻炼，而且人们需要同时注意脑力及体力的锻炼。由此可见，本文讨论的是为什么人们应该积极进行体力及脑力锻炼，故选项D为正确答案。文章第一段第一句虽然提到“when people are mentally engaged，biochemical changes occur in the brain...”，但只是说明当人们用脑时，人脑中会产生生物化学变化，但具体这种生物化学变化是怎样在人脑中产生的，并不是本文探讨的主要内容，故选项A不是正确答案。文章中并未提到过老年人应该接受特殊的脑力训练一事，相反，在文中第三段提到“specific training”的句子中，Fozard提出保持头脑的警觉性比接受专门的脑力训练对人更有意义，故选项B也不是正确答案。文章只是在最后提到“Intellectual activity actually influences brain-cell health and size.”，但除这一句话外，本文并没有更多地探讨智力活动是怎样影响到脑细胞健康的，所以选项C也不是正确答案。