Some scientists say there will not be enough land for Earth in the near future. So some other places should     1    (find) by us to live. While some scientists are considering building communities on the moon and Mars, other scientists feel independent space stations could bring many more     2    (benefit). 

So what is wrong     3     the moon or Mars? Firstly, the distances are a problem. The moon is about 384,000 kilometres from Earth. Mars is over 55 million kilometres away. The journey to the moon takes from four to eight days,     4     the one to Mars takes from six to eight months. It will be both time-consuming and     5    (danger) to get settlers to these distant places. Moreover, it takes a message up to 44 minutes to go from Earth to Mars,     6    (make) fast communication impossible. However,     7     space station circling Earth is just a few hours away,     8     makes the trip much cheaper and communication     9    (relative) easy. Furthermore, the absence of light at night on the moon and Mars isn’t a good thing either. On a space station, however, the sun’s energy can be made available     10    (support) mankind living there 24 hours a day.