it rain heavily tomorrow, we would have to put off the visit to the Forbidden City.
A. Were
B. Should
C. Would
D. Will
网友回答
A. Were
(答案→)B. Should
C. Would
D. Will
解析：考察虚拟语气和倒装。在条件状语从句中，如果与将来事实相反，条件句中有三种：过去时；were to do ;should+动词原形，主句使用“情态动词+动词原形”；要特别注意如果省略了if，句子要使用部分倒装的形式，把助动词，be动词，情态动词提之主语前。本题就是把if省略，把should提前。句意：如果明天的雨下得很大，我们就不得不不推迟到紫禁城的参观。故B正确。