These stocks could be near major inflection points.I disagree with the adage that "opportunity only knocks once." At least, I don't think it's always true with investing. That said, there are inflection points for some stocks after which things will never be the same.Looking for these kinds of once-in-a-generation investment opportunities? Here are three magnificent stocks to buy right now.1. Occidental PetroleumYou might be surprised to see an oil stock on this list. Aren't companies based on fossil fuels ...