Exercise 1: Fill in the blanks in the sentences.

1. If you don't leave now, you'll be late for school. 2. If it rains tomorrow, we'll stay at home. 3. If we don't call him, he'll be angry. 4. If you don't have lunch, you'll be hungry. 5. If he feels better, we'll invite him. 6. If you give me your address, I'll write to you. 7. If Paul phones his granny, she'll be happy.