The key answer of exercise 9

a)

• You shouldn’t listen to music on a bicycle, it isn’t safe.
• You shouldn’t eat hot, smelly food on public transport.
• You don’t have to give up your seat to old people, pregnant women or small children, but it is a kind thing to do.
• You have to buy a ticket to travel on public transport.
• You shouldn’t put your feet on the seats.
• You have to wear a seatbelt in the front and the back of a car.
• You shouldn’t leave your bags in everyone’s way on trains, buses, or planes.
• You should stand in a queue at the bus stop.

b) -