题目

Sally has a new bike and she likes sports. So she rides her bike to school every day. It takes her about 10 minutes. Jim, Sally’s brother, is shorter and thinner than her. But he likes sports, too. Every day he walks to school, and his home is about two miles from school. It takes him about twenty minutes. He thinks it helps him to keep fit and study well. Every morning, Sally and Jim get up at the same time, but Jim is faster than his sister. He leaves for school at seven. His sister goes to school at seven ten. They both get to school at about twenty past seven. (     ) 1. Sall 已知向量，则tana的值为 [　　] A． B． C． D．