题目

抛物线的对称轴是( )A. y轴 B. 直线x=?3 C. 直线x=?1 D. 直线x=1 答案：【答案】D【解析】抛物线y=(x-1)2-3是抛物线的顶点式，根据抛物线的顶点式可知抛物线y=(x-1)2-3的对称轴是直线x=1.故选C.--- Please tell Bruce he has won the first prize in the maths contest. ---          He never did so well before. A．Congratulations!                                         B．Good luck! C．That’s right.                                               D．What a good surprise!