It is difficult for doctors to

【题目】It is difficult for doctors to help a person with a hurt brain. Without enough blood, the brain lives only three to five minutes. Sometimes the hurt brain gets better by itself. More often the doctors can't fix the hurt brain. Sometimes they are afraid to try something to help. It is dangerous to work on the brain. The doctor might make the person worse if he works on the brain.

Dr. Robert    J. White, a famous professor and doctor, thinks he knows a way to help. He thinks doctors should try to make the brain become very cold. If it is very cold, the brain can live without blood for 30 minutes. This gives the doctors a longer time to do something for the brain.

Dr. White tried his idea on 13 monkeys. First he taught them to do different jobs. Then he opera-ted on them. He made the monkeys' blood go through a machine. The machine cooled the blood. Then the machine sent the blood back to the monkeys' brains. When the brain temperature was 10 degrees. Dr. White stopped the blood to the brain. After 30 minutes he turned the blood back on. He warmed the blood again. After their operations, the monkeys were like they were before. They were healthy and busy. Each one could still do the jobs the doctor had taught them.

Dr. White's idea works well on the monkeys. Are there other problems with human beings? Dr. White thinks doctors will use his idea on human beings. He thinks it will help people who have heart problems, too. A person doesn't have to die when his heart stops? doctors can start it again. The problem comes when the brain is without blood for three to five minutes—the person has a living body, but a dead brain. Maybe in the future, doctors will try Dr. White's idea. When the person's heart stops, the doctors will quickly try to cool the brain. They will have 30 minutes to start the heart again. Maybe there will be no problem with the brain.

【1】 People probably die when __________.

A. their brain dies

B. their heart stops

C. they stop breathing

D. their brain becomes very hot

【2】 Dr. White thinks his idea about cooling the brain will work because __________.

A. he has tried it on people

B. he has tried it on monkeys

C. he has tried it on heart problems

D. he has tried it on himself

【3】 Which of the following is not true?

A. Doctors can begin the heart again in five minutes.

B. Doctors can begin the heart again after 30 minutes.

C. Doctors can change patients' hearts.

D. Doctors can change a person's face.

【4】 According to the writer，__________.

A. it is not difficult to repair the brain damage

B. it is worse to make a mistake on the brain than any other part of the body

C. brain is not an important part in one's body

D. brain doesn't need blood