单选题 Only after a heated discussion ______ in solving the problem.
A. they did succeed B. did they succeed
C. had they succeeded D. they had succeeded

【正确答案】 B
【答案解析】[考点] 倒装结构。否定词如never等，及“only+状语”“so+状语(或表语)”等开头的句子要用倒装语序，故排除A，D。据题意，排除C，故选B。