There are many people in the world now. There will be a lot more people in the future. The earth will be very crowded and there will be a little room for each person. Maybe there will be standing room only on the earth 600 years later.

So man is thinking of a way to solve the problem.

Maybe man will go to stay on the moon one day. But there is on air, no plants, no life there. So scientists are doing experiments in many ways. They have to solve many problems before man can live on the moon .I’m sure our dream will come true in the future.

So now, we must work hard. And one day , maybe we can make great contributions for our world. At that moment, we will be proud of ourselves. That’s nice.