It is highly likely that John went to the hallway. It is probably not the case that Greg is a frog. Chances are about even that Brian is green. We doubt that if Greg is a frog, or Brian is green, then Sandra got the milk. There is little chance that if either Brian is green, or John went to the hallway, then Lily is a lion. There is a very good chance that if either John went to the hallway, or Greg is a frog, then Mary dropped the apple.
It is probably not the case that either John went to the hallway, or Sandra got the milk.
There is a very good chance that either John went to the hallway, or Sandra got the milk.
It is probably not the case that either John went to the hallway, or Sandra got the milk.
Either John went to the hallway, or Sandra got the milk.