_______ many times, he finally understood it

A.Told

B.Telling

C.Having told

D.Having been told

答案及解析： D

解析：

考查非谓语动词。根据句意可知先被告诉许多次，故用现在分词的被动Having been told，表示动作先后性。句意：被告诉了许多次，他最终理解了。