Restate the following rules in sentences with be supposed to.

1. No smoking

2. keep off the grass

3. No eating or drinking in this room.

4. Move to the rear of the bus.

5. Do not joke with airport personnel while your hand luggage is being inspected.

6. Use the stairs in case of fire. Do not use the elevator.

7. No littering.

8. Slower traffic keep right.

(Tư liệu tham khảo: Betty Schrampfer Azar. Understanding and Using English Grammar.3rd ed).