It was playing computer games that cost the boy plenty of time he ____ doing his lessons.

   A．might have spent    B．ought to have spent           C．must have spent    D．could have spent

It was playing computer games that cost the boy plenty of time he ____ doing his lessons.

   A．might have spent    B．ought to have spent        

C．must have spent    D．could have spent

It was playing computer games that cost the boy plenty of time he ____ doing his lessons.

1. A.
   might have spent
2. B.
   ought to have spent
3. C.
   must have spent
4. D.
   could have spent