Thank you very much for explaining to me the best choice.
I still have a few sentences I'm doubtful of. I included 7 doubts using question words. Thank you
1) Sometimes my parents aren't at home for (?) their work and so I have to stay at home alone with my brother.
2) I felt sorry for my mum because she has a broken leg (better: she broke her leg, she had a broken leg).
3) I finished primary school with an average mark of 9 out of (?) 10.
4) I was proud of myself on 24th July when I passed my driving test.
5) The teacher reprimanded me (= wrote a reprimand in the class register??)
6) It was the last sad moment in my life when my girlfriend broke up with me (?). While I was climbing a step I fell on the floor (?)(I fell down on the floor)