关于警察，下列说法错误的有( )A．警察的任务，是维护社会秩序，保卫国家安全 B．警

        Mark was walking home from school one day when he saw the boy in front of him fall over and drop all
of the books he was carrying, along with two sweaters, a basketball and a walkman (随身听). Mark stopped
and helped the boy pick up these things. Since they were going the same way, he helped to carry some of his
things. As they walked, Mark knew that the boy's name was Bill, and he loved computer games, basketball and
history, and he was having lots of troubles with his other subjects and that he had just broken up with his
girlfriend. 
        They arrived at Bill's home first and Mark was invited in for a coke and to watch television. The afternoon
passed happily with a few laughs and some small talks, then Mark went home. They often saw each other at
school, had lunch together once or twice, and then they both finished middle school. They ended up in the same
high school where they sometimes saw and talked with each other over the years. At last just three weeks           before they finished high school, Bill asked Mark if they could talk?
          Bill asked Mark if he still remembered the day years ago when they had first met." Did you ever think
why I was carrying so many things home that day?" asked Bill. "You see, I cleaned out my locker (锁柜)
because I didn't want to leave anything for anyone else. I had put away some of mother's sleeping pills and I was going home to kill myself. But after we spent some time together talking and laughing, I began to understand that
if I killed myself, I would have missed that time and so many others that might follow. So you see, Mark, when
you picked up those books that day, you did a lot more. You saved my life."

A. to have a basketball game
B. to his classroom 
C. to see Mark
D. back home