I can't possibly forget the days ———to pay a visit to your school ten years ago.如果题目是这样的话,答案应该是D.句子主干部分是“I can't possibly forget the days.” 而“———to pay a visit to your s...能不能说得再细点儿，嘿嘿，谢谢I can't possibly forget the days spent paying a visit to your school ten years ago.=I can't possibly forget the days that was spent paying a visit to your school ten years ago.I can't possibly forget the days cost to pay a visit to your school ten years ago.=I can't possibly forget the days that was cost to pay a visit to your school ten years ago.