`7.` If they were not absent now, they would meet the head master.

`8.` Unless I knew the number, I would not ring her up.

`9.`  Unless you study harder, you 'll get bad marks.

`10.` Unless this man is a driver, he can help you move by car.

`11.` Unless he practice writing every day, he can't improve his writing skill.

`12.` If you don't return this book to the library today, you’ll have to pay a fine.

`13.`  If you don't go out more often, you might fall ill.

7, If they weren't absent now, they would meet the headmaster

8, Unless i knew the number, i wouldn't ring her up

9, Unless you study harder, you'll get bad marks

10, If this man isn't a driver, he can't help you move by car

11, Unless he practices writting everyday, he can't improve his writting skill

12, If you don't return this book to the library today, you'll have to pay a fine

13, If you don't go out more often, you might .... ill