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

-- 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

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

1. A.
   might it be
2. B.
   could it be
3. C.
   could it have been
4. D.
   should it have been

— Do you still remember when we went to Nanjing?

— I can't remember now but ________sometime last summer?

1. A.
   might it be
2. B.
   could it be
3. C.
   could it have been
4. D.
   should it have been