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

问题补充：

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

答案：

A. might have spent

(答案→)B. ought to have spent

C. must have spent

D. could have spent

解析：本题考查的是虚拟语气的有关用法。Ought to / should + have +p.p表示“本来应该做却没有做到的事情”，有责备的含义。