21. The Internet can not be used for ____.

　　A. studying B. shopping C. thinking D. playing

22. The Internet was born in about________

　　A. 1960 B.1971 C.1980 D.1985

23. Which of the following is TRUE?

A. Students know the friends on the Internet very well

B. Few students like surfing on the Internet

C. Students use the Internet to make "unreal friends".

D. These "unreal friends" often meet each other.

24. What does the writer think of the Internet?

A. It is helpful, but we can not do everything on it

B. It can make students work harder

C. It is not good for students

D. It is wonderful

B

　 How would you like to learn more without having to study more? Here's how:

　1. Get to bed and go to sleep. Your performance, attention, and the ability to concentrate are damaged by lack of sleep. Teenagers need nine to 10 hours of sleep a night for best performance.

　2. Feed you head. The brain runs badly if it doesn't get enough fuel. That means protein(蛋白质)and complex carbs(复合碳水化合物)-eggs and wheat bread for breakfast, say, rather than sugary cereal(含糖的麦片粥) and orange juice. The biggest mistake teens make is not to have breakfast or to go for sugar, which raises blood sugar levels.

　3. Body exercise is brain exercise. Body exercise really improves brain performance, perhaps because it increases blood flow, or perhaps because it reduces stress and anxiety(焦虑). Twenty minutes of activity a day that raises your heart rate will do great good.

4. Learn now what you want to remember for the rest of your life. Teenage brains