5．It may be difficult to imagine by the year 2100，we will live on Mars．Our own planet，the Earth is becoming more and more （75）A and polluted．Luckily，we can start again and build a better world on Mars．Here is what life will be like．
Firstly，（76）D should be much better．Spaceships can travel at half the speed of light．It might take us two or three days to get to Mars．
Secondly，humans need food，water and air to live．Scientists should be able to develop plants that can be grown on Mars．These plants will （77）B the food and the air that we need．
There is a problem for us to live on Mars．Mars makes us much lighter than the Earth does．This will be dangerous because we could easily jump too high and fly slowly away into space．To prevent this，humans on Mars have to wear special shoes to make themselves（78）D
Life on mars will be better than that on the Earth （79）C．People will have more space．Living in a large building with 10bedrooms is highly possible．Many people believe that robots will do most of our work．
However，life on Mars may not be better than that on the Earth today．Food will not be the same meals will probably be in the form of pills and will not be as delicious as they are today．（80）B，space travel will make many people feel ill．The spaceship will travel fast but the journey to mars will probably be very uncomfortable．
| 75．A） crowded | B） modern | C） developed | D） serious |
| 76．A） dressing | B） eating | C） living | D） transporting |
| 77．A） destroy | B） produce | C） refuse | D） support |
| 78．A） quicker | B） prettier | C） lighter | D） heavier |
| 79．A） all the way | B） in this way | C） in many ways | D） by the way |
| 80．A） However | B） Besides | C） Nowadays | D） Immediately． |
