10. My father knows Kate's father. They (   ) to each other at a conference. 

• A、had been introduced
  
  

• B、are introduced
  
  

• C、were introduced
  
  

• D、have been introduced
  
  

48. When do pupils start their summer holidays?

• A、In August
  
  

• B、In July. 
  
  

• C、In September. 
  
  

• D、In the middle of July. 
  
  

55. (     )