If you go to fast food restaurant, you can see a lot of teenagers. Today,1teenagers are  2 because of their favorite food. Most teenagers 3junk food 4 a lot of fat, salt and sugar.

    5 bad eating habits are more than junk food. We find many teenagers eat6 Some don't have 7 before they go to school. During the day, some don't 8a proper meal for lunch. In a survey 9 one school, scientists found that over 65% of the students didn't have 10 healthy diet.

    Parents today also 11 about their children's diet. Some doctors give the following 12

    Teenagers shouldn't eat 13 junk food .Teenagers shouldn't eat food with much14 Salt can cause high blood pressure in the future.

Teenagers should eat food without much fat, oil and sugar.

    Teenagers15 to eat some fruits and vegetables every day. Fruits and vegetables are rich in vitamins and they have little fat.

已知圆（x﹣2）²+（y+1）²=16的一条直径通过直线x﹣2y+3=0被圆所截弦的中点，则该直径所在的直线方程为（　　）

电视政论片《大国崛起•工业先声》的解说词说：“牛顿为工业革命创造了一把科学的钥匙，瓦特拿着这把钥匙开启了工业革命的大门。”这表明(　 　)

三军可夺帅也，____。（《论语》）

某热气球体积为1000m³，能载重6900N，若空气密度ρ=1.29kg/m³，则热气球受到的浮力为　 ____　N，它的自重为　 ____　N．（g取10N/kg）