问题补充:
(·宁夏银川一中高三第四次考试) scores of times, but he still couldn understand it.
A. Having explained
B. Having been explained
C. Though it was explained
D. It was explained
答案:
A. Having explained
B. Having been explained
C. Though it was explained
(答案→)D. It was explained
解析:D考查句子结构。本句中的but是并列连词,由此可知but前后都是完整的分句。表转折意义的句中,but与though不能同时用,故D项正确。