We often think of future. We often wonder what the world will be like in a hundred years. Think of space, perhaps a permanent station on the moon will have been set up. Perhaps people will be able to visit the moon as tourists. Cheap rockets for space travel will have been developed, permitting long journeys throughout the solar system. When that time comes, people will be taking holidays in space and visiting other planets.
Great progress will have been made in medicine, too. Perhaps a cure will have been discovered for the most terrible of all diseases-cancer. Pollution is a problem we must solve. In a hundred years it will have been controlled.
The world will have been developed-even the Antarctic. There will be large cities in the Antarctic. We already have supersonic (超音速的) flight, but in a hundred years we will have supersonic land travel as well.
We will have used up most of the earth's land to build our cities, so floating cities will have been built. The Japanese already have plans for cities of this kind. And there will be cities under the sea. The first of these will have been completed.
