For many young people sport is a popular part of school life. Being in one of the school teams and playing in matches is very important. If someone is in a team it means a lot of extra practice and often spending a Saturday or Sunday away from home, as many matches are played then.
   In can also involve travelling to other towns to play against other school teams and then staying on after the match for a meal or a drink. Sometimes parents, friends or the other students will travel with the team to support their own side.
   When a school team wins a match it is the whole school. It means the whole school feels proud, not only the players. It also means a school becomes famous for being good at certain sports and students from that school may end up playing for national and international teams, so that the school has some really famous names.

线l经过原点和点（﹣$\sqrt{3}$，1），则它的斜率为（　　）