It was not until the subprime loan crisis(次贷危机) had caused great damage to the American financial system ______ Americans realized the severity (严重性) of the situation.
【正确答案】
B
【答案解析】 “not until the subprime loan crisis(次贷危机) had caused great damage to the American financial system”是被强调部分，因此后面用that引导主句。句意：直到次贷危机给美国的金融系统造成了巨大危害时，美国人才意识到局势的严重性。