-- Do you still remember when we went to Nanjing?I can’t remember now but sometime la

问题补充：

-- Do you still remember when we went to Nanjing?

--- I can’t remember now but sometime last summer?

A. might it be

B. could it be

C. could it have been

D. should it have been

答案：

A. might it be

B. could it be

(答案→)C. could it have been

D. should it have been

解析：考查情态动词。句意：—你还记得我们什么时候去南京的吗？—我记不清楚了，但是也许是去年暑假的某个时间？根据句意说明对过去所发生的情况的推测，故使用“情态动词+have done”；could have done也许做了某事/本可以做某事；should have done本应该做某事；实际上却未做；表示的是虚拟语气。故Ｃ正确。