31. A problem
32. B 

           Is there life on Mars? Many people have wondered about this (31) question . Some writers of science-fiction think of people from Mars as little green creatures. Others imagine 'Martians' as monsters with many eyes.
           In studying this planet, astronomers have found that life may be possible (32) on Mars. The first indication of this is that Mars has seasons, just like Earth. In other words, Earth's seasons, such as spring or summer, occur on Mars too. Because these seasons exist, it may be possible for vegetation and other higher life forms to be found on Mars.
           Astronomers also think that perhaps a small (33) amount of water vapor could be found on Mars. In 1887, an Italian astronomer, Giovanni Schiaparelli, discovered markings on Mars' surface. These markings looked like canals. This finding led astronomers to believe that since water exists on Mars, life forms could exist as well.
          (34) However, there are others who feel that life on mars is not possible. This is because there is little or no trace of oxygen on the planet. In 1965, the Mariner IV capsule managed to take (35) photographs of the planet. It discovered that the only forms of life found are vegetation like fungi and mosses. Nevertheless, people remain fascinated by the idea that there could one day be life on Mars.