A.drive a car | B.take a bus |
C.take a submarine | D.swim |
A.build houses | B.learn to swim |
C.learn to drive the submarine | D.solve some problems |
A.They will have difficulty in breathing. |
B.They will become quite short. |
C.They will feel cold. |
D.They will feel tired. |
A.more comfortable | B.less comfortable |
C.easier | D.more crowded |
A.There are also some problems for people to solve if they want to live on the moon. |
B.The sea is noisy and crowded for man to live in. |
C.Some of the problems are very hard to solve. |
D.Some scientists believe submarines will be popular in the future. |