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