单选题 The fire was finally brought under control, but not ______ extensive damage had been caused.
A. before B. since C. after D. as

【正确答案】 A
【答案解析】[解析] 句子的大意为：火势终于被控制住了，但还是造成了巨大的损失。not before表示“在这之前”，所以A项符合题意。