A. Brush your teeth right before you go to bed in the evening.
B. Have as few of your teeth pulled out as possible.
C. Have your teeth X-rayed at regular intervals.
D. Clean your teeth shortly after eating.

A. They provide only suggestions and ideals but never put them into practice.
B. People need pay more attention to the knowledge of environment preservation.
C. Desperate pollution in many areas is to deprive mankind of a good future.
D. Survival of mankind relies on their ability to find new resources.