Fleas<br>My dog has fleas and constantly scratching himself. I took my dog to the veterinarian office. The veterinarian gave my dog two shots. Eventually the fleas started to die. My dog finally stop scratching himself.
There are no fleas left
From the context we only know that the fleas are starting to die, not that they have all died. The system has likely assumed that when they said 'the fleas started to die' it meant all fleas have died.
( z1 flea :ARG1-of ( z2 leave ) )