3 Read and complete with the words in the box. have to / must mustn't don't have to Australia is an enormous country and some people live hundreds of miles from a city. If they get ill, they (a)...... have to / must see a doctor, but this can be difficult. If people can't travel to a city, the Flying Doctors (b)........ fly to them. The doctors (c) ...... fly the plane because a pilot always goes with them. You (d)........ pay for the service because it's free. There are about 60 planes to take doctors all over Australia, so people who are ill (e)........ wait long for help. Many remote areas also have a medical chest. Before you use it, you f) ..... speak to a flying doctor by phone. And you (g)......... use the medicine for animals, it is only for people.​