Anchor: two male skaters walk on sidewalk
Entailed: Two male skaters are going for a walk.
Contradiction: Two male skaters are skating on the sidewalk.
Contradiction: The crates are purple.
Contradiction: You are quite dumb despite being seen as the opposite. 
Contradiction: Men working on fixing their scooters
Contradiction: Miss Howard interrupted the man's pleasing thoughts by entering unexpectedly.