13. —Who do you think has eaten my cake, father?

 —It (   ) be your younger sister. 

• A、must
  
  

• B、should
  
  

• C、will
  
  

• D、may
  
  

36. Mr. Brown (   ) . 

• A、works on his own in a bank
  
  

• B、 lives in a bank and works on his own
  
  

• C、lives by himself and works in a bank
  
  

• D、lives with his sister and works by himself
  
  

53. (      )