单选题 It was not until the subprime loan crisis (次贷危机)______ great damage to the American financial system that Americans______the severity of the situation.
【正确答案】 B
【答案解析】解析：考核时态的掌握。次贷危机发生在先，人们意识到金融体制在后，而且句子的时态是一般过去时故选择B。