many times but he still couldnt understand it.A. Having been toldB. Though he had been

问题补充：

many times, but he still couldn understand it.

A. Having been told

B. Though he had been told

C. He had been told

D. Having told

答案：

A. Having been told

B. Though he had been told

(答案→)C. He had been told

D. Having told

解析：句中的but是连词，要连接两个相同的结构，本题中连接两个分句。