Premise: If Esther failed Philosophy 101(A), she would drop out of school.(B)
Premise: She has left school, (B)
Conclusion: She failed the course. (A)
Attack: Failing the course may not be the reason for why Esther has left school. She might have suffered from other things, like an unexpected accident accountable for her leaving.
Premise:
If a person is given a proper upbringing by one's parents(A), he or she will treat others with respect(B).
Premise: If a person treats others with respect, (B)
Conclusion:
He or she has indeed been given a proper upbringing.(A)
Attack: There are some people suffering from poor education, or growing without parents who also know how to respect others, which defies the unwarranted conclusion and its premise.