Only after they had discussed the matter for a few hours a decisionA. they reachedB. did t

问题补充：

Only after they had discussed the matter for a few hours a decision

A. they reached

B. did they reach

C. they reach

D. do they reach

答案：

A. they reached

(答案→)B. did they reach

C. they reach

D. do they reach

解析：考查Only的倒装句。Only放在句子，且强调状语的时候，后面的主句使用部分倒装句。句意：只有他们讨论那个事情几个小时以后，才得出一个决定。