Anchor: A rider on a dirt bike is doing a maneuver in midair over a dirt mound.
Entailed: The dirt bike is in midair.
Contradiction: The rider is on ice.
Contradiction: The man pulled himself free before his arm could give. 
Contradiction: A pair of girls wait around in a cafe.
Contradiction: The skateboarder is playing video games.
Contradiction: Private pensions, accumulated assets, or other resources should supplement Social Security benefits.