用方框中所给的词适当形式填空。 watch, instead, grow, because, many, they,  for,  study,  easy,  do life in the 21st century will be different from life in the 20th century, because many changes will take place. The population is __1__ fast. There will be more and more people in the world and most of __2__ will live longer than before. Computers will be much smaller and more useful. And computer __3__ will be one of the important subjects at school. People will work fewer hours than they __4__ in the 20th century, and they will have more free time for sports, __5__ TV and traveling. Traveling will be much __6__ . And many more people will go to other countries __7__ holidays. There will be changes in our food, too. __8__ land will be used for building new towns and houses. Then there will be less room for cows and sheep, so meat will be more expensive. Maybe no one will eat it every day, __9__ they eat more vegetables and fruit. Maybe people will be healthier. Work in the future will be different, too. erous and hard work will be done by robots. __10__ of this, many people will not have enough work to do. This will be a problem.