问题补充:
it rain tomorrow, we would have to put off the visit to the Yangpu Bridge.
A. Were
B. Should
C. Would
D. Will
答案:
A. Were
(答案→)B. Should
C. Would
D. Will
解析:句意:如果明天下雨,我们将不得不取消参观杨浦大桥。前半句是对将来情况的虚拟,正常语序是If it should rain tomorrow。省略 if 后,要将 should提到主语之前,引起倒装。所以选B。