it rain heavily tomorrow we would have to put off the visit to the Forbidden City.A. Wer

问题补充：

it rain heavily tomorrow, we would have to put off the visit to the Forbidden City.

A. Were

B. Should

C. Would

D. Will

答案：

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。