A dog is perched up against a tree looking at the top .
Chances are about even that a dog chased a squirrel up a tree and is waiting for it to come back down .
Chances are about even that a dog chased a squirrel up a tree and is waiting for it to come back down .
It is highly unlikely that a dog chased a squirrel up a tree and is waiting for it to come back down .
A dog chased a squirrel up a tree and is waiting for it to come back down .