阅读理解。 Young people can have problems with their minds. Some students become worried because they have to study very hard. Others have trouble getting on well with people like their parents and classmates. Liu Wei, a Junior 2 student from Hefei, could not understand his teacher and was doing badly in his lessons. He became so worried about it that he started to cut his finger with a knife. Another student, 14-year-old Yan Fang from Guangzhou, was afraid of exams. She got very worried, and when she looked at the exam paper, she couldn't think of anything to write. A recent report from Jiefang Daily says about 18% of Shanghai teenagers have mental (心理的, 精神的) problems. Their troubles include (包括) being worried and very unhappy, and having problems in learning and getting on with people. Many students who have problems won't go for advice or help. Some think they will look stupid (愚蠢) if they go to see a doctor. Others don't want to talk about their secret. Liang Yuezhu, an expert on teenagers from Beijing Anding Hospital has the following advice for teenagers: * Talk to your parents or teachers often * Take part in group activities and play sports * Go to see a doctor if you feel unhappy or unwell 1. The students who often become worried or have trouble getting on with others may have . [     ] A. mental problems B. a headache C. knives with them D. no parents 2. Liu Wei cut his finger with a knife because . [     ] A. he was afraid of his teacher B. he wanted to frighten his parents C. he was so worried about his studies D. his finger was badly hurt 3. Yan Fang's problems happened whenever . [     ] A. she studied very hard B. she had exams C. she talked with her parents D. she thought of something 4. Students who have problems won't ask others for help because . [     ] A. they won't let others think they are stupid B. they don't think doctors can help them C.they don't want to tell their secret to others D. both A and C 5. Liang Yuezhu's advice tell us that . [     ] A. it's better for the students who have mental problems to join others B. it's unnecessary for them to be with others C. only group activities and sports can help them D. teachers and parents can't do anything about mental problems