题目

方程|x-3|=6的解是（ ）A. 9 B. ±9 C. 3 D. 9或-3 答案：【答案】D【解析】∵，∴或，解得： 或.故选D.According to our school rules, no student ____ be permitted to carry mobile phones in class.A. will B. must C. may D. shall