A survey has found that in adolescence (青春期) a lack of physical activity is connected with emotional and behavioral problems. More than 7,000 teenagers in Finland took part in the survey that judged their levels of physical activity and mental and emotional health. Boys who reported less than one hour of physical activity a week were more likely to be anxious and sad than boys who were more active. Girls who were not active had similar problems, and were more likely than boys who were not active to have sleep problems and break school rules. The researchers concluded that both boys and girls who are not active are more likely than active ones to have social and attention problems. “Adolescence is already a difficult stage of life-emotionally, mentally and physically,” study author Marko T.Kantomaa said in the American College of Sports Medicine. “Mixing that with negative mental and emotional effects brought on by lack of physical activity does not help young people enter adulthood smoothly. Physical activity could be a highly effective and relatively easy way to help that transition and could lead to healthy habits for one’s whole life,” Kantomaa said. Researchers said that evidence suggests that an increase in physical activity helps reduce problems of sadness and anxiety in both adolescents and adults. “It seems that there is a psychological(心理的)and physiological(生理的)connection that helps explain the beneficial effects of exercise on mental health,”Kantomaa said. 1. The first paragraph leads us to believe that________. A. a lack of physical activity may cause many mental problems B. a lack of physical exercise is common among teenagers C. girls have more physical and mental problems than boys D. inactive boys are more likely to break rules than inactive girls 2. Which of the following problems may NOT be caused by a lack of activity according to the passage? A. Anxiety.     B. sleeplessness.    C. Inattention.   D. unkindness. 3. From the passage we can conclude that___________. A. boys take more physical exercise than girls B. teenagers who aren’t active spend a lot of time studying C. plenty of physical activity is effective in developing healthy habits D. physical exercise is the only way to cure mental problems 4. The underlined word “transition” in the fourth paragraph is closest in meaning to“_______”. A. change      B. condition       C. balance       D. activity