_天津成考网

57.(  )

Cultural exchange plays an important role（）promoting relation between the two countries.

• A、 in
  
  

• B、on
  
  

• C、at
  
  

• D、to
  
  

 Researchers are trying to（）what’s wrong with their experiments. 

• A、pull out
  
  

• B、call out
  
  

• C、take out
  
  

• D、 figure out