My crib sheet for answering questions: Oui = Agreement to a question
Si = Yes to a negative. "Is the sky not blue? Si, it is blue."
Moi aussi = Me too
Moi non plus = Me neither
Pas = "not" for a partial negative answer "Is the sky blue everyday?" Not everyday.
I find the use of "si" the most difficult to learn but it would be very handy in English. Sometimes we don't know if someone answered in the affirmative to our question. This can lead to all kinds of situational comedies. "Don't you want to have dinner, sweetie?" "Si, I want to have dinner." Yup, works for me.
