还原法

　　有些题目是以疑问句、倒装句、强调句、被动句、感叹句等形式出现的。解答此类题时，可还原其本来面目，变回正常语序（陈述句或主动语态），答案便一目了然。

　　Had they known what was coming next，they _______ second thoughts. （2012浙江卷）

　　A. may have B. could have C. must have had D. might have had

　　【解析】D.考查虚拟语气。将 Had they… next 还原为 If they had known what was coming next，我们可以看出本题是考查与过去事实相反的虚拟语气。对过去进行推测时，从句形式为had done，主句形式为would / should / might have done.句意为：如果他们知道下一步会发生什么事情，他们也许会三思而后行的。

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