There is a very good chance that Mary left the apple. Chances are about even that Greg is a swan. It is probably the case that Gertrude is a cat. Chances are about even that if either Mary left the apple, or Gertrude is a cat, then Julius is green. It is highly unlikely that if Greg is a swan, or Mary left the apple, then Lily is a lion. It is unlikely that if Greg is a swan, or Mary left the apple, then Bill went to the kitchen.
We doubt that either Julius is green, or Mary left the apple.
We believe that either Julius is green, or Mary left the apple.
We doubt that either Julius is green, or Mary left the apple.
Either Julius is green, or Mary left the apple.