it rain tomorrow, we would have to put off the visit to the Yangpu Bridge.
A. Were
B. Should
C. Would
D. Will
网友回答
A. Were
(答案→)B. Should
C. Would
D. Will
解析：
试题分析:句意：万一明天下雨的话，我们将不得不推迟去杨浦大桥的参观。根据主句would have to可知此句是对将来的虚拟，主句用would+动词原形，从句用should/were to do+动词原形，而从句可以省略if，把should或were提前，故答案选B。