"Opportunity" is an event that you can take advantage of - it must be acted upon in order to achieve the desired outcome. "Possibility" is something which may happen, but it the outcome is uncertain. "Capability" is the potential to perform an act. "Ability" is the potential turned into reality using training or practice etc. In other words "a skill" For example: children are capable of swimming, but they must first practice to in order to have the ability to swim.

okay let's me explain you. Manchester united have 0 possibility of winning league next season. they don't have capabilitie to playing attacking football. And they have abilitie to park the bus when even they are losing. hope you understand....