—My old friend White is going to visit me.—We havent seen each other five years.A. since

问题补充：

—My old friend White is going to visit me.

—We haven seen each other five years.

A. since B after C. for

答案：

解析：句意：我的老朋友怀特要来看我。我们彼此没见面有五年啦。Since自从，后面可跟一段时间的起点；after在之后，后面可跟一段时间或一个时间点；for后面必须跟一段时间。所以选C。