______many times ,he finally undertood it

題目：

______many times ,he finally undertood it
A.Told B.Telling C.Having told D.Having been told
求原因,還有我想知道是不是句首不能用完成時還是什麼的,求指教

解答：

D.Having been told
被動語態,表示他處於被動位置,被告知.