There are many people in the world now．There __1__ a lot more people next century．So the earth will be very __2__ and there will be a little room for each person．Maybe there will be only __3__ room on the earth in 600 years．That will be a very serious __4__．
So man is __5__ of a way to solve the problem．
The moon is the satellite（卫星）of the earth．Man will probably go to __6__ there some day．But there is no air，no plants and no life on the moon．So __7__ are doing experiments in many ways．They __8__ solve many problems __9__ man can live on the moon．I'm sure our dream will __10__ next century．Do you think so?
1．A．are B．will be C．has D．will have
2．A．small B．popular C．crowded D．noisy
3．A．standing B．sitting C．bed D．bath
4．A．example B．fact C．question D．problem
5．A．saying B．telling C．thinking D．knowing
6．A．see B．sleep C．work D．live
7．A．tutors B．adults C．astronauts D．scientists
8．A．may B．have to C．could D．are able to
9．A．before B．after C．since D．till
10．A．come in B．arrive at C．come true D．become real