阅读下面短文，从短文后各题所给四个选项（A、B、C和D）中，选出可以填入空白处的最佳选项，并在答题卡上将该项涂黑。
Life in the year 2050 will be 1 from today. Between then and now many changes will take place. But what 2 the changes be?
The population(人口)is growing fast. There will be 3 people in the world and most of them will live 4 than people live now.
Computers will be much 5 and more useful, and there will be at least one in every home. And computer studies will be one of the most important subjects in 6 then.
People will work 7 hours than they do now and they will have more free time for sports, 8 TV and traveling.9will be 10 cheaper and easier. And more people will go to other countries on 11.
12 will be changes in our food, too. More land will 13 for building new towns and houses. Then there will be less land for keeping cows and sheep, so meat will be more expensive. Maybe no one will eat it every day. Instead they will eat more fruit and vegetables. Maybe people will be healthier.
Work in the future will be different, too. Dangerous and hard work will be done 14 robots. Because of this, many people will not have enough work to do. This will be a 15.
2C（g）若经 2 s（秒）后测得 C 的浓度为 0.6 mol·L-1 ，现有下列几种说法： ① 用物质 A 表示的反应的平均速率为 0.3 mol·(L·s)-1