If it rains today, I'll stay at home.
If he is busy now, I will come back tomorrow.
If I have time, I'll visit my parents this afternoon.
If it is warm tomorrow, we'll go to the beach.
If it is cold, you must wear warm clothes.
If he doesn't do his homework, he can not go to the party.
If she doesn't call you, you can call her.
If you work hard, you may become a millonaire someday.
If you spend more than you earn, you'll become a poor man.
If they don't invite you, you must not go.