Only after they had discussed the matter for several hours a decision.
A. they reached
B. did they reach
C. they reach
D. do they reach
网友回答
A. they reached
(答案→)B. did they reach
C. they reach
D. do they reach
解析：考查倒装句。Only的倒装有两个条件：only放在句首，且强调状语时，后面使用部分倒装。本题两个条件都符合。句意：只有在他们讨论这个问题几个小时以后他们才得出结论。