It’s only six o’clock now; Little Tom should be up though because he for nine hours.A.

问题补充：

It’s only six o’clock now; Little Tom should be up ,though, because he for nine hours.

A. has been sleeping

B. had been sleeping

C. has slept

D. had slept

答案：

(答案→)A. has been sleeping

B. had been sleeping

C. has slept

D. had slept

解析：考查时态。根据语境可知汤姆一直在睡，现在还在睡，故用现在完成进行时，故选A。