题目

曲线y=x2-1与y=1-x3在点x=x0处的切线要么互相平行要么互相垂直，则x0的取值集合为A.{-，0，}                            B.{ ,0，}C.{-，}                                  D.{ ，} 答案：A The watch ________ me two hundred yuan. [　　] A．spent B．cost C．paid for D．lost