虛擬語氣表示動作或狀態不是客觀存在的事實，而是說話人的主觀愿望、假設或推測等。它是中學英語課本中經常出現的一種語言現象，但對中國學生來說，卻是一個難點。筆者根據自己的教學實踐，對高中階段常見的各種虛擬語氣的運用情況作了一個大致的小結，并分別舉例說明。
        1. 表示假設(If)
        eg. If I were a bird, I could fly in the air. 
        如果我是一只小鳥，我就能在空中飛行。
        If I had come here yesterday, I would have seen him. 
        如果我昨天來這，我就已經見到他了。
        2. 表示祝愿（常用“May+動詞原形”）
        eg. May good luck be yours!  祝你好運！
        May you be happy!      祝你快樂！
        3. I wish + (that)  賓語從句
        If only 要是……該有多好
        eg. I wish I were a bird. 但愿我是只小鳥。
        He wishes he hadn’t lost the chance.
        他真希望沒有失去機會。
        If only I could pass the examination.
        要是我能通過考試該有多好。
        If only we had 1,000,000 dollar!
        要是我們有100萬美元該有多好!
        4. but for, without, otherwise等
        eg. But for your help, I would have failed.
        要不是你的幫助，我已經失敗了。
        Without air, nothing could live.
        要是沒有空氣，什么也不能生存。
        He worked very hard; otherwise he might have failed. 
        他刻苦工作，不然他就失敗了。
        5. 一個堅持insist；兩個命令order，command；三個建議suggest，advise，propose；四個要求demand，require，request，ask。
        (1)動詞 + (that) 賓語從句
        eg. He demands that this (should) be done at once. 他命令要馬上做這件事情。
        I suggest that the job (should) be finished next week. 我建議下周完成這項工作。
        注意：當insist表示“堅持說、認為”，suggest表示“表明、暗示”時，不用虛擬語氣而用陳述語氣。
        eg. The look on his face suggested that he was satisfied with what I had done for him.他臉上的表情表明他對我為他所做的事情感到滿意。
        He insisted that he was honest.  他堅持說他是誠實的。
        (2)在上述動詞相應的名詞，如 order，command，suggestion, advice, proposal, requirement等后接that表語從句、同位語從句中。
        eg. My suggestion is that we (should) go there at once.
        我的建議是我們立刻去那兒。
        It is my proposal that he be sent to study further abroad.
        我提議派他去國外進一步學習。
        (3)It’s+上述動詞的過去分詞+ that ．．．（should）．．．
        eg. It’s suggested that the meeting (should) be put off. 有人建議會議應該被推遲。
        It is required that nobody (should) smoke here.要求所有人不要在此抽煙。
        6. It is (about,high) time that ... sb did sth或sb should do sth （注意should不能省略）
        eg. It is high time I went home now. = It is high time I should go home now. 現在正是我回家的時間了。
        7. as if/as though
        eg. It looks as if it were going to rain.（虛擬）天看上去好像要下雨。（事實上不下雨）
        It looks as if it is going to rain.（陳述）天看上去好像要下雨。（確實快下雨了）
        8. would rather＋從句
        eg. I would rather you went there instead of me.
            我情愿你代我去那兒。
           — Would you mind my smoking here?
           — I’d rather you didn’t.
           — 你介意我在這兒抽煙嗎？
           — 我情愿你不要。
        9. 部分情態動詞＋have done，表示“本……”
        如：should/ought to/could/might等＋have done
        eg. You should have arrived here earlier. 你本該早點到這來。（事實上來晚了）
         I could have worked out the problem.我本能夠解決這個問題的。（事實上沒解決）
        10. It’s +形容詞或名詞+ that．．．（should）．．．
        用于該句型的形容詞常見的有：necessary, impor-tant, natural, strange, surprising等；常見的名詞如：a pity，no wonder等。
        eg. It is important that you (should) learn English well. 對你來說，學好英語是非常重要的。
        It is quite natural that he (should) think so. 他這樣想也是很自然的。 
        It is strange that so wise a man (should) make such silly mistakes. 
        真是奇怪，如此聰明之人竟會犯如此愚蠢之錯誤。