38. We can know from the information given in the passage that the moon must be about (   ) away from us. 

• A、one million km
  
  

• B、350,000 km
  
  

• C、300,000 km
  
  

• D、400,000 km
  
  

51. (    )

16. The concert has already begun. You should have come a little bit (   ). 

• A、early
  
  

• B、much earlier
  
  

• C、more earlier
  
  

• D、earlier