2. 外语
  3. 1 Dementia, a general decrease in intellectual abilities, involves impairment of memory, judgment, and social functioning. The t

1 Dementia, a general decrease in intellectual abilities, involves impairment of memory, judgment, and social functioning. The t

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问题 1 Dementia, a general decrease in intellectual abilities, involves impairment of memory, judgment, and social functioning. The two most frequent causes of dementia are Alzheimer’s disease and multiple small strokes, but it can also be caused by depression, drug intoxication, alcohol abuse, head trauma, and advanced stages of AIDS.
2 Studies from China, Japan, Sweden, Italy, and the United States suggest that between 3 and 6 percent of all adults over age 65 show significant signs of dementia. The researchers concluded that as many as 47 percent of all adults 85 and older suffer from some level of dementia, and medical experts generally agree that the rate of dementia is highest in adults over 85.
3 The cause of approximately half of all cases of dementia, Alzheimer’s disease involves specific processes in the brain, most prominently a kind of tangling of the fibers in the nerve cell bodies. This tangling, which contributes to a major loss of synapses, occurs mostly in the areas of the brain that regulate new learning and memory. While all aging adults appear to have some such tangling, those that show symptoms of Alzheimer’s disease have far more. This tangling short-circuits many of the brain pathways, interfering with the person’s ability to remember even well-learned skills, such as driving a car and using a fork.
What is the main purpose of paragraph 2?
选项 A、To list the symptoms of dementia
B、To give rates of dementia in older adults
C、To define the various types of dementia
D、To explain how dementia progresses
答案B
解析 The purpose of the paragraph is to give rates of dementia in older adults. Clues: ...between 3 and 6 percent of all adults over age 65...; ...as many as 47 percent of all adults 85 and older... the rate of dementia is highest in adults over 85.
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