A.R                                       B.{x∈R|x≠kπ,k∈Z}

C.［-1,0)∪(0,1]                    D.{x|x≠0}

A.{x|-1≤x≤1}                     B.{x|x≤-1,或x≥1}

C.{x|0≤x≤1}                      D.{-1,1}