用频率为ν的单色光照射某种金属时，逸出光电子的最大动能为E_K，已知普朗克常量为h，则该金属的逸出功为____；若改用频率为2ν的单色光照射此种金属时，则逸出光电子的最大动能为____．

    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.