Anchor: operating system engaged in symmetric multitasking.
Entailed: Operating systems can multitask.
Contradiction: Operating systems aren't able to be programmed to multitask.
Contradiction: A boy is sitting in the stands
Contradiction: 3 band members perform on stage.
Contradiction: Two businessmen are sitting down to a vegetarian meal at a restaurant.
Contradiction: Gertis was the most powerful of the warring city states.