помогите пожалуйста. нужно 5 предложений в кондишнл 3. Заранее Спасибо)

If I had known how  had all that  finished I would have tried to avoid it.
If I had learnt English better I wouldn't have lost time looking up words.
If you had seen her ,you would have changed your mind about her.
If  he had forgotten his book, he should have taken yours.
If they have missed lessons,they should have taken extralessons.