Plot: 2012/01/20 Headlines: GOP Candidates Debate Ahead of South Carolina Primary; Ex-Wife: Gingrich Asked for Open Marriage; Perry Exits GOP Race, Backs Gingrich; Second Officer Backs Trial for Manning; Afghans Protest Deadly NATO Raid; France Suspends Training of Afghan Troops After Shooting; Syrian Protests Follow More Killings; Arab League Extends Monitoring Mission; Top U. S