根据短文内容,选择最佳选项。
What will our life be like in 50 years? No one knows the answer exactly(确切的), but we are sure that it will be very different from the life today. My brother Jill White makes some predictions. Here are some of his ideas
First, people will have less work to do, and robots will do most work. People will use robots to makers, do the housework, look after sick people and teach students. People will spend most of their time playing sports and traveling. So people will become stronger and healthier, and they will live to be about 200 years old.
Second, cars will become very small and computers will control(控制)their speed(速度). So there will be fewer accidents on the road, Planes will be very popular, and most people would like to take them to ravel.
Third, people will be able to live in the sea, on the moon or on Mars. The earth won't be crowded or noisy. So there will be much space for people to plant trees. There will be less pollution, and the air will become much fresher.
Finally, water shortagewill become one of the most serious problems. If people don't save water now ere will be water wars(战争)in 50 years.