If you turn off all the lights, you will not pay more money.
If she doesn't wear warm clothes, she will have a cold.
If you are not careful, you may have an accident.
If you don't phone your parents, you will have trouble.
If she doesn't whisper, everyone will know what she's saying.
If you stay here, you will feel safe.
If you don't pay your electricity bill today, your electricity will be cut off.