单选题 With the purchasing power of many middle-class households ______ behind the cost of living, there was an urgent demand for credit.
A. leaving B. levering C. lacking D. lagging

【正确答案】 D
【答案解析】[解析] 句子的大意为：由于许多中产阶级家庭的购买力落后于生活成本，所以就有了迫切的信贷要求。本题考查动词与介词(behind)的搭配。A项leaving“离开，留下，舍弃”；B项levering“使用杠杆，撬”；C项lacking“缺少，不足”；D项lagging“落后，迟延”。所以D项符合题意。