There are many people in the world now． There (1) （be） a lot more people next century． The earth will be very (2) （crowd）so there will be a little room (3) each person． Maybe there will be only standing room on the earth 600 (4) （year）later． That will be a very serious problem． (5) man is thinking of a way to solve the problem．
The moon is the satellite of the earth． maybe man will go (6) （live） on the moon one day． But there is no air， no plants (7) no life there． So scientists (8) （do） experiments now in many ways．they have to solve many problems (9) man can live on the moon． I am sure our dreams (10) （come） true in the next century．