54. (    ) 

40. The main idea of this passage is (   ).

• A、warfare is a "law of nature"
  
  

• B、warfare is not a "law of nature"
  
  

• C、warfare does not control human population
  
  

• D、none of the lowlier animals, except ants, practice warfare upon their own species
  
  

2. (     )

• A、longer
  
  

• B、need
  
  

• C、nasty
  
  

• D、nag