Anchor: Never in the annals of medicine has a viral plague been stopped by any therapy.
Entailed: According to medical history, therapy has never stopped a viral plague. 
Contradiction: Therapy is effective in treating viral plagues. 
Contradiction: A window is completely open.
Contradiction: A man is taking part in a kayak competition.
Contradiction: One kayak heading for another on a foggy riverbank.
Contradiction: I have spent money on equipment to take pictures.