问题补充:
,but he still could not understand it.
A. He had been told many times
B. Having been told many times
C. Told many times
D. Although he had been told many times
答案:
(答案→)A. He had been told many times
B. Having been told many times
C. Told many times
D. Although he had been told many times
解析:考查从句和非谓语动词。从该题中but一词看,前面应该是一个句子,而不是分词作状语。