【题目】Not until recently _______the development of tourist-related activities in the rural areas.
A.they had encouraged
B.had they encouraged
C.did they encourage
D.they encouraged

【答案】C
【解析】句意：直到最近他们才鼓励在农村地区开展与旅游业有关的活动。当not until所引导的时间状语放在句首时，主句要使用部分倒装。因此可以排除A项和D项，过去完成时是指过去的过去，不合题意，所以答案是C。