第一部分：阅读理解（共两节，满分50 分）
第一节 (共20小题，每小题2分，满分40分)
A
Alzheimer’s disease is a major national health problem. Nearly 2 million Americans over the age of 65 have Alzheimer’s disease. It is a leading cause of death among the elderly. But Alzheimer’s disease is not confined（限于）to the aged . There may be a million or more people under the age of 65 suffering from the disease.
