39. If the information given in this passage is correct, when we look at a star at night (   ). 

• A、we will notice that it is not moving
  
  

• B、we cannot tell whether or not it still exists
  
  

• C、it is four years that the light we can see will reach us
  
  

• D、it will be brighter than the moon
  
  

55. (   )

42. The Polar Bears like to swim all the year round, for (   ). 

• A、they can remain young
  
  

• B、it is an easy way to keep the body warm in winter
  
  

• C、they find it enjoyable and interesting
  
  

• D、they might meet fewer troubles in life