我国城市燃气管道压力分级标准中，中压A的压力范围应为（）。

患者，女，20岁，昏睡、呕吐2小时，既往体健。查：皮肤潮红，呼吸不规则，有苦杏仁味，考虑可能为（）.

A.安眠药中毒

B.酒精中毒

C.煤气中毒

D.氰化物中毒

E.有机磷农药中毒

急性根尖周脓肿阶段的临床表现，除外（）。

A.自发性剧烈性跳痛

B.不敢咀嚼，牙有伸长感

C.局部淋巴结可有肿痛

D.患牙Ⅱ～Ⅲ度松动

E.出现颌面部蜂窝织炎

下列实验设计和结论相符的是 [ ]

A. 在含FeCl₂杂质的FeCl₃溶液中通足量Cl₂后，充分加热，除去过量的Cl₂，即可得到较纯净的FeCl₃溶液  

B. 现在媒体谈论的PM2.5是指环境空气中空气动力学当量直径≤2.5um的颗粒物。直径为2.5um的颗粒物分散到空气中能形成胶体

C. 某无色溶液中加Ba(NO₃)₂溶液，再加入稀盐酸，沉淀不溶解，则原溶液中一定有SO₄^2-

D. 加入氢氧化钠溶液并加热，产生的气体能使湿润红色石蕊试纸变蓝，一定有NH₄⁺  

阅读理解。

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

for only three to five minutes. More often the doctor 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 ℃, 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 what 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

B. 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 operations on monkeys first

B. 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 can _____. [ ]

A. last as long as 30 minutes

B. keep the brain's blood warm

C. keep the patient's brain healthy

D. help monkeys do different jobs

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

    a. send the cooled 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, a

夹具的基本作用是定位和（）。

A.换向

B.夹紧

C.导向

D.对刀