题目内容：
回答题。More about Alzheimer's Disease
Scientists have developed skin tests that may be used in the future to identify people with Alzheimer's disease and may ultimately allow physicians to predict 51 is at risk of getting this neurological disorder.
The only current means of 52 the disease in a living patient is a long and expensive series of tests that eliminate every other cause of dementia.(痴呆 )
" Since Alois Alzheimer described the 53 nearly a century ago, people have been trying to find a way to 54 diagnose it in its early stages, " said Patricia Grady, acting director of the National Institute of Neurological Disorders and Stroke in Bethesda, Maryland. "This discovery, if 55 , could prove a big step forward in our efforts to deal with and understand the disease. "
Alzheimer's is the single greatest 56 of mental deterioration in older people, affecting between 2. 5 million and 4 million people in the United States 57 . The devastating disorder gradually destroys memory and the ability to function, and eventually causes death. There is currently no known 58 for the disease.
Researches 59 that the skin cells of Alzheimer's patients have defects that interfere with their ability to regulate the flow of potassium in and out of the cells. The fact that the cell defects are present in the skin suggests that Alzheimer's 60 from physiological changes throughout the body, and that dementia may be the first noticeable effect of these changes as the defects 61 the cells in the brain, scientists said.
The flow of potassium is especially 62 in cells responsible 63 memory formation. The scientists also found two other defects that affect the cells' supply of calcium, another critical element.
One test developed by researches calls for growing skin cells in a laboratory culture and then testing them with an electrical detector to determine if the microscopic tunnels that 64 the flow of potassium are open. Open potassium channels create a unique electrical signature.
A spokesman for the Alzheimer's Association said that if the validity of the diagnostic test can be proven it would be an important 65 , but cautioned that other promising tests for Alzheimer's have been disappointing.
A．}what
B．one
C．it
D．who
参考答案：
答案解析：