关于典型支气管哮喘的临床表现，下列哪项描述是正确的（）。 A.发作性吸气性呼吸困难伴

历史学家认为17世纪后期科学思想革命的胜利为启蒙运动提供了先决条件,17世纪后期科学思想革命中最重要的先驱是                       

A．达尔文

B．牛顿

C．伽利略

D．法拉第

用放大镜观察一个30°的角，角变大了．______．

阅读理解。

     It is difficult for doctors to help a person with a damaged brain. Without enough blood, the

brain lives for only three to five minutes. More often the doctors can't fix the damage. Sometimes

they are afraid to try something to help because it is dangerous to work on the brain. The doctors

might make the person worse if he operates on the brain.                                                            

     Dr. Robert White, a famous professor and doctor, thinks he knows a way to help. He thinks

doctors should make the brain very cold. If it is very cold, the brain can live without blood for

30 minutes. This gives the doctor 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

operated 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's

temperature was 10°C, 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 had been before. They were healthy and busy. Each one could still do the jobs the doctor

had taught them.       

1. The biggest difficulty in operating on the damaged brain is that _______.         

A. the time is too short for doctors

B. the patients are often too nervous

C. the damage is extremely hard to fix

D. the blood-cooling machine might break down

2. The brain operation was made possible mainly by _______.

A. taking the blood out of the brain       

B. trying the operation on monkeys first

C. having the blood go through a machine    

D. lowering the brain's temperature

3. With Dr. White's new idea, the operation on the damaged brain _______.

A. can last as long as 30 minutes        

B. can keep the brain's blood warm

C. can keep the patient's brain healthy    

D. can help monkeys do different jobs

4. What is the right order of the steps in the operation?

a. send the cooled blood back to the brain

b. stop the blood to the brain

c. have the blood cooled down

d. operate on the brain

A. a, b, c, d            

B. c, a, b, d       

C. c, b, d, a            

D. b, c, d,

从经济内容看，下列属于流动负债账户的有( )

A．“应付债券”

B．“预付账款”

C．“应付股利”

D．“短期借款”

E．“应付职工薪酬”

左室各壁中，哪个壁最厚（）。

A.前壁

B.侧壁

C.下壁

D.间壁

E.后壁