问题补充：
---- I Tom for three days. Is he ill?
---- I’m afraid so. The doctor said he needed .
A. haven’t seen; to be operated
B. haven’t seen; to be operated on
C. didn’t see; operating
D. haven’t see; operating
答案：
A. haven’t seen; to be operated
(答案→)B. haven’t seen; to be operated on
C. didn’t see; operating
D. haven’t see; operating
解析：句意：我已经三天不见汤姆了。他病了吗？——恐怕如此。医生说他需要一个手术。结合语境可知上文描述的是现在已经完成的动作，故用现在完成时态。下文主语是动作对象，故用被动语态。Operate不能直接接宾语，需加介词on，故选B。
