问题 单项选择题

已知曲面z=4-x2-y2上点P处的切平面平行于平面2x+2y+z-1=0,则点P的坐标是().

A.(1,-1,2)

B.(1,1,2)

C.(-1,1,2)

D.(-1,-1,2)

答案

参考答案:B

辨析题

2008年初的罕见冰冻,导致了很多送电线路受损,不能供电,严重影响人民群众的生产生活。湖南省电力公司工人罗海文、罗长明、周景华在高压线路上人工除冰时,不幸殉职。这三位工人这样献出生命不值得。

                                                                                                                                                              

                                                                                                                                                             

                                                                                                                                                             

                                                                                                                                                            

单项选择题