技巧点拨

（1）当if引导的虚拟条件从句中含有had, were, should时，如将if省略，则要将had, were, should等移到主语前，构成倒装句。如：
Had you come yesterday, you would have seen him.

（2）表示建议、命令、要求的词无论是动词形式、名词形式还是过去分词形式，其后的名词性从句均需使用虚拟语气。

知识精练

The Bakers arrived last night. If they’d only let us know earlier, ______ at the station.

A. we’d meet them B. we’ll meet them

C. we’d have met them D. we’ve met them

【答案】C。解析：考查虚拟语气。句意：贝克一家昨晚到了。要是他们早点通知我们，我们就在车站接他们了。本句是if引导的非真实条件句，they’d是they had的缩写，由此可知是与过去事实相反，主句用“情态动词+have done”的形式，故选C，we’d have是we would have的缩写。