求助一道虚拟语气的题目

渣渣要考gmat

9) 5． Developing nations in various parts of the world have amassed $700 billion in debts; at stake, should a significant number of these debts be repudiated, is the solvency of some of the worlds largest multinational banks.
(A) should a significant number of these debts be repudiated, is
(B) should a significant number of these debts be repudiated, are
(C) should they repudiate a significant number of these debts, are
(D) if there is a repudiation of a significant number of these debts,would

be
(E) if a significant number of these debts will be repudiated, is

答案是A ，should提前了和倒装没问题，但是想问下大神们

if a significant number of these debts should be repudiated，是对将来的虚拟吧，后面主句不应该would / should / might / could + 动词原形吗？？

为什么这里用一般现代式啊 ？？求指教！

虚拟语气的时态：

时间	从句谓语形式	主句谓语形式
将来	动词过去式(be用were) should + 动词原形 were to + 动词原形	would / should / might / could + 动词原形
现在	动词过去式(be 用 were)	would / should / might / could + 动词原形
过去	had +动词过去分词	would / should / might / could have + 动词过去分词

yangyi920629

似乎是条件状语从句跟虚拟语气弄混了？

yangyi920629

http://forum.chasedream.com/thread-458231-1-1.html