Lemma 2: Let h be a subgroup of the group G. Then gH=H and Hg=H for Vg∈G. Proof: (p: H>Hg, o (h)=h*g Lemma 2：Let H be a subgroup of the group G. Then |gH|=|H| and |Hg|=|H| for gG.  Proof: :H→Hg, (h)=hg