It is unlikely that Mary dropped the milk. It is probably not the case that Brian is a swan. Chances are slight that Gertrude is a cat. It is highly unlikely that if Mary dropped the milk, and Gertrude is a cat, then Greg is white. We believe that if Mary dropped the milk, or Brian is a swan, then John picked up the apple. It is impossible that if Mary dropped the milk, and Brian is a swan, then Sandra got the football.
It is unlikely that mary dropped the milk, or Greg is white.
It is unlikely that mary dropped the milk, or Greg is white.
It is certain that mary dropped the milk, or Greg is white.
Mary dropped the milk, or Greg is white.