We still remember once round the famous tower when we were young.A. having takenB. to be

问题补充：

We still remember once round the famous tower when we were young.

A. having taken

B. to be taken

C. having been taken

D. to have taken

答案：

A. having taken

B. to be taken

(答案→)C. having been taken

D. to have taken

解析：句意：我们仍然记得当我们年轻的时候，我们曾经被领着参观著名的塔。这里是短语remember to do记得去做某事，表示将要做的事情；remember doing/having done记得做过某事，表示事情已经做过了；这里句子的主语与take之间是被动关系，故排除AD；根据句意可知这是过去的事情，所以事情已经发生了，故选C。