题目

A teenager needs to have a sense of independence in their life to feel secure（安全的）. To some teenagers independence means a lot to them, and I think that some parents don’t allow their teenagers enough independence.Independence has something to do with freedom. Some kids are not allowed to go anywhere alone, and the only thing their schedule includes is going to school, coming home, going to sleep, and repeating the process the next day. Parents tend to be afraid that their kids can get hurt if they go outside into the world. But if parents control their kids too much, they may neve当你双手抓住单杠身体下垂时，你的肱二头肌和肱三头肌的状态是A.肱二头肌收缩，肱三头肌舒张B.肱二头肌舒张，肱三头肌收缩C.肱二头肌和肱三头肌同时收缩D.肱二头肌和肱三头肌同时舒张