题目

— May I smoke here? —  No, you__________, only do that in the smoking room. A. can          B. need        C. mustn't        D. couldn't 答案：A整数x，x1，x2，x3，…，x2002，x2003满足条件：x=0，|x1|=|x+1|，|x2|=|x1+1|，|x3|=|x2+1|，…，|x2003|=|x2002+1|，求：|x1+x2+x3+…+x2002+x2003|的最小值．