表示说的话不是事实，或者是不可能发生的情况，而是一种愿望、建议或与事实相反的假设等。一般常用于正式的书面语中。
１、 虚拟语气的构成
注：如果条件从句谓语动词包含有were或had, should, could有时可将if省去, 但要倒装。如：
Had you (If you had) invited us, we would have come to your party.
２、 虚拟语气在各种从句的应用（１） 在主语从句中用来表示惊奇、惋惜、理应如此等，其谓语形式是"should(可省) ＋动词原形"，常用于以下三种句型中。句型一：It is necessary (important, natural, strange, etc) that…句型二：It is a pity (a shame, no wonder, etc) that…句型三：It is suggested (requested, proposed, desired, etc) that… 如：It is strange that he (should) have done that.
It is a pity that he (should) be so careless.
It is requested that we (should) be so careless.
（２） 在宾语从句中用于suggest, propose, move, insist, desire, demand, request, order, command等动词后的宾语从句中，表间接的命令和建议。其谓语形式是"(should) 动词原形"。如：I suggest that we (should) go swimming.
（３） 在表语从句中，表示间接的命令，要求、请求、建议、决定等，主句中的主语通常是suggestion, proposal, request, orders, idea等。从句谓语形式是"(should)＋动词原形"。如：His suggestion is that we (should) leave at once.
（４） 在同位语从句中，谓语形式是"(should)＋动词原形"。如：We received order that the work be done at once.
（５） 在It is time that…句型中，其谓语动词形式是"动词的过去式"或 "should ＋动词原形",should不可省。如：It's time (that) we went ( should go) to school.
II． 例题例１ We had hoped that he ____ longer.
A. stays B. have stayed
C. stayed D. would stay
解析：该题正确答案为Ｄ。had hoped表示"本希望"，同样用法的动词还有think, expect等，后面的句子需用虚拟语气
例２ "Mary wants to see you today"."I would rather she ____ tomorrow than today."
A .comes B .came
C. should come D. will come
解析：该题正确答案为Ｂ。would rather后面的从句需用虚拟语气，用动词过去时表示。
例３ Had she been older, she ____ it better.
A had done B might have done
C might do D would do
解析：Had she been older
= If she had been old.
故该题正确答案为Ｂ。
声明：来源于网络！
