阅读理解 We often think of future. We often wonder what the world will be like in a hundred years' time. Think of space,  perhaps a permanent (永久的) 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(太阳系). When that time comes, people will be taking holidays in space and visiting other planets. Creat 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' time it will have been controlled. All the world will have been developed-even Antarctica. There will be large cities in Antarctica. We already have supersonic (超音速的)  flight,  but in a hundred years' time we will have supersonic land travel as well. We will have used up most of the earth's land tobuild 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.       . 1. We will have developed _ in a hundred years' time, permitting long journeys all over the solar system. A. cheap rockets for space travel B. a plane C. a spaceship D. a satellite 2. Man will also have supersonic land travel . A. in a year B. about half a century later C.in the year 2050 D. about a century later 3. The last paragraph mainly talks about _ . A. we'll make good use of space on the earth B. cities under the sea C. Japan will first build floating cities D. earth's land is in danger