为了区别CO（可能混有氧气）与CO2两瓶无色气体，下列方法中可行的是（） A．伸

阅读理解。

     If you go to a fast food restaurant, you will probably see a lot of teenagers. Today, many teenagers are

overweight, and some of this is because of their bad eating habits. Most teenagers love food with a lot of

fat, oil, salt and sugar. People often call this kind of food "junk food".

     But bad eating habits go beyond fast food. We find many teenagers eat unhealthily. Some don't have

breakfast before they go to school. During the day, some don't have a proper meal for lunch. In a recent

survey at one school, scientists found that over two-thirds of the students didn't follow a healthy diet. They

didn't like vegetables, and many of them didn't like to eat fruits. They preferred to eat food with a lot of salt,

sugar or fat.

     Parents today also worry about their children's diet. Some doctors give the following advice: 

    Teenagers shouldn't eat too much junk food.

    Teenagers shouldn't eat food with too much salt. Salt can cause high blood pressure in the future. 

    Teenagers should eat food with less fat, oil and sugar.

    Teenagers need to eat some fruits and vegetables every day. Fruits and vegetables are rich in vitamins and

have little fat.

    Teenagers need to drink more milk. Milk will help their bones grow.

    Teenagers need to eat breakfast every day. This is good for their body and mind.

1. The main reason why many teenagers are overweight is that they eat too much ______. [ ]

A. milk and sugar

B. fruits and sugar

C. vegetables and salt

D. fat, oil, salt and sugar

2. In a recent survey at one school, what did the scientists find? [ ]

A. Teenagers don't have breakfast before going to school.

B. Teenagers have a bad eating habits.

C. Teenagers don't like eating vegetables.

D. Teenagers don't have a proper meal for lunch.

3. Why is milk important to us? [ ]

A. Because it will help the bones to grow.

B. Because it is good for the body and mind.

C. Because it is with less fat, oil and sugar.

D. Because it is junk food.

4. In this passage, doctors advise teenagers to eat more ______. [ ]

A. food with less salt and milk

B. food with much fat and sugar

C. vegetables and fruits

D. food with no salt and oil

5. The best title for this passage should be ______. [ ]

A. Keeping good habits

B. Fast food is good

C. Unhealthy food is bad

D. Advice on healthy eating

（5分）有下列各组物质：

A．O₂和O₃；

B．¹²₆C和¹³₆C;

C．冰醋酸和乙酸；

D．甲烷和庚烷；E.CH₃-CH₂-CH₂-CH₃和CH₃CH（CH₃）CH₃； F.淀粉和纤维素。

（1）互为同位素的是               （2）互为同素异形体的是       

（3）互为同分异构体的是           （4）同一物质是         

（5）互为同系物的是          

在明确诊断前，在指定场所进行医学观察的是

A．鼠疫、霍乱和炭疽
B．甲类传染病病人和病原携带者、乙类传染病病人中的艾滋病病人、炭疽中的肺炭疽病人
C．对疑得甲类传染病病人
D．对除了艾滋病病人、肺炭疽患者以外的乙类
E．丙类传染病病人

降压药胍乙啶主要作用于

A．中枢α-受体
B．毛细小动脉
C．神经节
D．RAS系统
E．交感神经系统

设备风险评估是分析设备的（），进而综合评估设备风险的大小和确定风险的等级。

A.运行情况

B.重要度

C.故障情况

D.健康度