We doubt that Sandra dropped the apple. It is improbable that Bernhard is gray. It is probably the case that John left the milk.
It is probable that either Bernhard is gray, or John left the milk.
It is probable that either Bernhard is gray, or John left the milk.
There is little chance that either Bernhard is gray, or John left the milk.
Either Bernhard is gray, or John left the milk.