A．               B．               C．               D．（0，1）

11． 曲线的离心率的取值范围是

C．[0，]                                                  D．[1，]

       A．[0，1]                                                       B．[0，2]

10．函的值域是

A．6                           B．15                          C．                        D．

9．展开式中的系数是

A．9                           B．12                          C．15                          D．18

8．正四棱锥的底面边长等于，侧面与底面成60°的二面角，此四棱锥体积为

A．                         B．                         C．                       D．