Anchor: a skateboarder grinds a rail.
Entailed: A skateboarder does a sick trick.
Contradiction: A boy rides his bikes along a wall.
Contradiction: A skateboarder is sitting down.
Contradiction: A skateboarder doing a flip off a ramp.
Contradiction: A skateboarder falls down a ramp.
Contradiction: A biker is grinding a rail.