11. I didn’t eat lunch, I feel hungry now.
–> If I had eaten lunch, I wouldn’t feel hungry now.
12.  I only come if they invite me.
–> Unless they invite me, I won’t come.
13. He didn’t revise all his lessons, he failed the exam.
–> If he had revised all his lessons, he wouldn’t have failed the exam.
14. The park is over there, only 5 minutes’ walk.
–> If you walk to the park, it will take you 5 minutes.
15.  If you don't leave me alone, I'll call the police
16. If you arrive at the office earlier than I do, please turn on the air-conditioner.
Should………you arrive at the office earlier than I do, please turn on the air-conditioner.....
17. The children don’t go to school in the snowy weather.
If it …………were not for the snowy weather the children wouldn't go to school....
18. He died so young; otherwise, he would be a famous musician by now.
Had …he died soyoung he would be a famous musician by now