It seems very unlikely to happen, but if it________ , we need to be well-prepared.
A、should
B、could
C、must
D、might
【正确答案】：A
【题目解析】：原句的意思是“看起来应该不会发生，但是万一发生了，我们需要做好准备。”should用于虚拟语气句子中，有“万一、竟然、就、该”等意思。例如：Should it rain tomorrow (或If it should rain tomorrow ) ,the meeting would be postponed.（万一明天下雨，会议就推迟。）因此我们选择A. should
