Help understanding my French homework?

My teacher likes to give out homework on subjects before she teaches them(so we're just teaching ourselves) and I have no idea what I am doing here. I went back and reread the grammar structure lesson but nothing is making sense or connecting. For example; the first one I answered le retrouvé since the... show more My teacher likes to give out homework on subjects before she teaches them(so we're just teaching ourselves) and I have no idea what I am doing here. I went back and reread the grammar structure lesson but nothing is making sense or connecting.

For example; the first one I answered le retrouvé since the pronoun is singular masculine so it wouldn't change the verb but it was marked wrong. So then I tried l'ai retrouvé because I forgot about avoir and that was wrong too. I just don't understand what I should be doing or what I'm doing wrong. I only have one chance left to get this right and currently, I'm 1/6.

If someone could maybe walk me through the first one I think I would understand it a bit better. I don't want just an answer, I want an explanation.

Thank you to anyone whose read everything and still decides to help.
2 answers 2