Alzheimer’s disease（早老性痴呆病）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．
At one time．people suffering from the disease were said to be“getting old”．The disease was thought to be a natural part of growing old，but it is now known that Alzheimer’s disease strikes young and old alike．It is an organic disease that destroys brain cells．
Alzheimer’s disease affects the patient’s memory，speech and movement．In the beginning stages of the disease，the patient may seem slightly confused．He may have trouble in speaking．
Then the patient’s memory begins to fail．He may forget dates，telephone numbers，names and plans．   
As the disease progresses．the patient may not recognize his family and friends．These symptoms（症状）often cause terrible anxiety in the patient．He may feel lost and frightened．Sometimes the patient reacts with wild and bad behavior．
In the last stages of the disease．the patient may not be able to take care of himself．He may have lost the ability to speak and walk．
Scientists don’t know exactly what causes Alzheimer’s disease．It may be caused by a virus or a poisonous substance in the environment．At present，there is no cure for the disease．But there are ways to slow its progress．Exercise and physical treatment can help the patients of this disease．
72．The main idea of the passage is that Alzheimer’s disease______________．
A．is a terrible part of the aging process    B．is an organic disease that affects young and old
C．can be cured by physical treatment     D．causes forgetfulness
73．All of the following are symptoms of Alzheimer’s disease EXCEPT___________．
A．forgetfulness                       B．difficulty in speaking
C．loss of sight                        D．loss of the ability to walk
74．According to the passage，which of the following may be a cause of Alzheimer’s disease?
A．Poisons produced by the brain．       B．Getting old．
C．A virus．                          D．Lack of exercise．
75．The progress of Alzheimer’s disease can be slowed by_____________．
A．operation                          B．a change in environment
C．medicines                         D．physical treatment and exercise