When you are in England, you must   be very careful   in the streets because the traffic goes on the left. Before you cross the street, you must look to the right first and then the left. If the traffic lights are red, the traffic must stop . Then the people on foot can cross the road. If the lights are green, the traffic can go and people on foot mustn't   cross. In the morning and in the evening, when people go to or come back from work, the streets are very busy. The traffic is the most dangerous then. When you go by bus in England, you have to be careful, too. You must always remember the cars drive on the left. In many English cities, there are big buses with two floors. You can sit on the second floor. From there, you can see the city very well. That'll be very interesting. If the traffic lights are green, the traffic  _  .
can go must be careful mustn't cross must stop