下列关于溶液的说法正确的是（ ） A．从一杯质量分数为10%的食盐溶液中倒出一半

阅读理解。

                                                               IMPROVE ON SLEEP

      Good health needs good sleep. Going to bed before you're tired. Not eating or reading in bed. Go to bed at

the same time before midnight and get up at the same time. Your body likes routine (常规) for a good night's

sleep. 

                                                                STAY FREE OF FLU

      Studies show that a cold or flu virus (病毒) can live on our hands for long. So wash all parts of your hands

often with soap and water. For more ways to prevent the spread of flu, please call. HealthLine at 1800 848 1313.

                                                               ORAL (口腔) HEALTH

      Brush your teeth twice daily and visit the dentist at least once a year. The mouth is a mirror of disease. The

oral examination is not only for the health of teeth, but the whole body. For more of it, please visit www.

mydr. com. au. 

                                                                      FIT FOR LIFE

      Studies have shown that many diseases have something to do with less or no physical (身体) activity. Try

to do it for 30 minutes a day, 5 days or more a week. For more information, please call HealthLine at 1800 438

2000.

1. If you want to get a good sleep, you'd better _______. [ ]

A. go to bed after you're tired

B. go to sleep at midnight

C. follow the bedtime routine

D. eat something or read in bed

2. To prevent from catching a cold or flu, it's good for you _______. [ ]

A. to clean your fingers often

B. to brush your teeth twice daily

C. to get up early every morning

D. to wash all parts of your hands

3. You should visit the dentist at least once a year, because _______. [ ]

A. the oral examination is necessary

B. you don't often brush your teeth

C. some diseases may be in the mirror

D. you don't have a good night's sleep

4. Studies have shown that many diseases have something to do with _______. [ ]

A. having no oral examination

B. washing hands with cold water

C. sleeping too late sometimes

D. doing little physical activity

5. When you want to learn more about the flu, you can _______. [ ]

A. visit www. mydr. com. au

B. call HealthLine at 1800 848 1313

C. visit the dentist in your place

D. call HealthLine at 1800 438 2000

分解因式：（a+2）（a-2）+3a=         ．

关于德国的叙述正确的是 [ ]

A、现代化工业高度发达，是世界上经济实力最强的国家

B、发展工业所需的原料、燃料都依靠进口

C、埃森、杜伊斯堡是鲁尔区重要工业中心

D、汉堡是位于莱茵河下游的最大港口城市

分析不同纬度海区初级生产力的季节分布特征及其原因。

下列哪一选项效力等级最高（）。

A、宪法

B、法律

C、刑法

D、行政法