many times but he still couldn’t understand it.A. Though he had been toldB. Having been

问题补充：

many times, but he still couldn’t understand it.

A. Though he had been told

B. Having been told

C. Having told

D. He had been told

答案：

A. Though he had been told

B. Having been told

C. Having told

(答案→)D. He had been told

解析：本题考查句子结构和连词。因为后面有连词but，说明前面应该是一个句子。，因为BC两项都是非谓语动词短语，排除ＢＣ；而but又不能和though同时使用，故排除A