It seems to me you understood how the second conditional works but there are some areas for improvement here. I think you should pay more attention to verb patterns. If you look up the word 'choose' in the oxford dictionary it will tell you that you can 'choose between A and B' and not 'among'. It should also be 'choose something', not 'to something'. http://www.oxfordlearnersdictionaries.com/definition/english/choose?q=choose

I If had to choose someone to do something, I would choose to him. (I have just taken out the extra "to", but the grammar is correct) If had to choose between a private school and state school, I would prefer to go to private school. (Again, I have changed the prepositions - at and among - but the grammar is correct). IF I had to do a long trip , I would prefer to go by plane. (perfect) If I had to live in a modern flat or old flat ,I would prefer to live in a modern flat. (perfect). If I had to eat fast food or pasta, I would prefer to eat pasta. (Perfect) Now let me ask you a hypothetical question and see if you can answer it too. Would you prefer to have 4 legs (and no arms) or 4 arms (and no legs)?? Tom

Hi, hope this helps: I If had to choose to someone to do something, I would choose to him. If I had to choose someone to do something, I would choose him. If had to choose among a private school and state school, I would prefer to go at private school. If I had to choose between a private school and state school, I would prefer to go to a private school. IF I had to do a long trip , I would prefer to go by plane. If I had to go on a long trip , I would prefer to go by plane. If i had to live in a modern flat or old flat ,I would prefer to live in a modern flat. If I had to live in a modern flat or an old flat , I would prefer to live in a modern flat.