高三复习之情态动词&虚拟语气一.情态动词的用法1.表推测：现在过去肯定must+V原型must+havedone否定can’t+V原型can’t/couldn’t+havedone可能性may+V原型may/might+havedone2.表虚拟should/shouldn’thavedoneneed/needn’thavedonecouldhavedoneoughttohavedone二.虚拟语气1.if引导的虚拟条件句情况从句主句与现在事实相反过去时（be动词用were）would/could/should/might+动词原型与过去事实相反过去完成时（haddone）would/could/should/might+havedone与将来事实相反过去时；should/wereto+动词原型would/could/should/might+动词原型注意：①省略if的情况：当虚拟条件句中有should;had;were时，可以省略if，而把should；had；were提到主语前，变为倒装句②含蓄条件句：with；without；butfor等表达条件③错综条件句：主从句时间不一致2.表建议，命令，要求等的单词后接名词性从句suggest；order；insist；suggestion；等should+动词原型3.wish/ifonly/asif的虚拟语气与现在的事实相反用过去时与过去的事实相反用过去完成时与将来的事实相反用would、could+动词原型4.wouldrather的虚拟语气：与现在和将来的事实相反用过去时与过去的事实相反用过去完成时5.Itis+adj/n+that从句（strange/important/natural/asurprise等）：should+动词原形/shouldhavedone6.It's(high/about)timethat...:用过去时或should+动词原形
