It’s looking more and more like “Argo” is a lock for the best picture Oscar. Ben Affleck’s political thriller notched another win Sunday, winning the Writers Guild of America’s adapted screenplay award. It previously swept the top prize at the Golden Globes, the Directors Guild of America, the Screen Actors Guild, and the Producers Guild of America. (Mark Boal won the Writers Guild prize for original screenplay for “Zero Dark Thirty,” director Kathryn Bigelow’s movie about the CIA’s hunt for Osama bin Laden.) A few weeks ago, you’ll recall, Ben’s brother Casey Affleck predicted “Argo” would win the Oscar. “I don’t think [Ben] can be stopped,” Casey said. “It’s a great movie, he did a great job directing it, and there’s a lot of good will for him. I think people like him.” We think so, too. The Academy Awards will be held this coming weekend in LA.