Anchor: The cone is formed by small limestone slabs set in a spiral without mortar to bind them.
Entailed: Small limestone slabs, set in a spiral, form the cone.
Contradiction: The cones use a dense mortar to help them bind. 
Contradiction: Clinical trials are never conducted among hospitalized patients.
Contradiction: The dog is mean.
Contradiction: A boy playing tennis.
Contradiction: When Susan woke up, Jon had been gone for three months.