39. This selection was probably written to (   ). 

• A、show how lazy cats are
  
  

• B、talk about the habits of cats
  
  

• C、tell about famous people and their habits
  
  

• D、persuade people to take naps
  
  

54. (    )

15. (   ) he has limited technical knowledge, the old worker has a lot of experience. 

• A、Although
  
  

• B、Unless
  
  

• C、As
  
  

• D、Since