题目

 I paid a visit to Mrs Smith yesterday evening. She didn’t look _______, but she said she was getting on all right.A. as worried as ever        B. as happy as usualC. happier than                 D. as happily as usual 答案：B对于实数和，定义运算“*”： 设，且关于的方程为恰有三个互不相等的实数根、、，则的取值范围是（     ）A．B．C．D．