题目

— Do you know Grace well? —Yes. She is 8-year-old girl and she can play guitar. A . /; a B . an; / C . an; the D . a; the 答案：C关于x的方程3x2-6（m-1）x+m2+1=0的两实根为x1、x2，若|x1|+|x2|=2，求m的值．