1 I'll call the police if you don't leave me alone !
-> Unless you leave me alone, I'll call the police
2 I didn't have an umbrella with me and so i got wet
-> If I had an umbrella with me, I wouldn't get wet
3 You press this button to stop the machine
-> If you press this button, the machine will stop
4 I didn't know her number so i couldn't phone her
-> If I knew her number, I could phone her
5 Provided that you leave an address we will be able to contact you
-> Unless you leave an address, we won't be able to contact you