p1:若复数z满足 ∈R,则z∈R;
p2:若复数z满足z2∈R,则z∈R;
p3:若复数z1 , z2满足z1z2∈R,则z1= ;
p4:若复数z∈R,则 ∈R.
其中的真命题为( )
(Ⅰ)当复数z为实数时,求m的值;
(Ⅱ)当复数z为虚数时,求m的值;
(Ⅲ)当复数z为纯虚数时,求m的值.