1虛擬語氣—時態(tài)退格
例：
If he were indoors，he wouldn't feel so cold.
他要是在室內就不會覺得冷了。
If anyone had been in his position，he would have done the same.
任何處在他位置的人都會這樣做的。
If it were to rain tomorrow，I would stay at home.
明天萬一下雨，我就待在家里了。
注：用with,without,under,but for等表示虛擬條件，并列連詞or,otherwise含虛擬條件意義，
替換了if時候，也不要忘記，后方句子仍用虛擬。
注：在虛擬條件句中,如果出現(xiàn)有were,had,should,可以省去if,把這些詞放在句子前面,構成虛擬倒裝句。
Should he act like that again,he would be fined.
=If he should act like that again,he would be fined.
2虛擬語氣—從句should省略
當主句謂語動詞為表示愿望、建議、命令、要求等意義的特定標志詞時,其賓語從句謂語動詞要用（should）+動詞原形的虛擬語氣形式。
常見的此類標志詞有：
一堅持（insist等）,
二命令（command,order等）,
三建議（advise, suggest,propose等）,
四要求（demand,require,request,ask等）。
另外像decide,desire,intend,recommend等也有這類虛擬用法。
例
Mother insists that the seats（should）be booked in advance.
媽媽堅持要預訂座位。
注：當suggest意為“表明,暗示,說明”;insist意為“堅持說,堅持認為”時,從句謂語動詞用陳述語氣。
3特殊句式
?wish后的賓語從句謂語動詞也用虛擬語氣形式,表示與事實相反的一種愿望。（時態(tài)退格即可）
?would rather,would prefer等表示希望或婉轉責備的動詞后的賓語從句要用虛擬語氣形式：用過去時表示與現(xiàn)在或將來事實相反的情況;用過去完成時表示與過去事實相反的情況。
?在以as if,as though引導的方式狀語從句（如果主句的謂語動詞是連系動詞,
如be,feel,look,seem,sound等,那么as if,as though引導的就是表語從句）中,當表示非真實情況時,用虛擬語氣,與wish后賓語從句謂語動詞形式相同。（與現(xiàn)在相反,用一般過去時,be動詞多用were;與過去事實相反,用had+過去分詞;與將來可能相反,用would/could/might+動詞原形。）
例：
She sings as if she were a singer.
她唱起歌來就像一位音樂家似的。（與現(xiàn)在事實相反）
注：當as if引導的從句表示真實情況時,就用陳述語氣。
It looks as if it is going to rain.看上去天好像要下雨。
?由even if,even though引導的讓步狀語從句中,表示與所發(fā)生的事實相反時,應用虛擬語氣,其構成形式與條件句中虛擬語氣的構成形式相同。
例
Even though I had been with you then,I could not have done much for you.
即使當時我跟你在一起，也不能為你做更多的事情。（與過去相反）
注：如果even if,even though表示的是真實情況就用陳述語氣。
Even if it rains,I will go.即使天下雨，我也要去。
?If only引起的感嘆句
相當于How I wish +賓語從句,意思是“但愿……;要是……就好了”,用法和wish基本相同,可表示對現(xiàn)在、過去和將來的虛擬,比wish具有更強烈的感情色彩。
If only he could come!（對將來的虛擬）
他要是能來就好了!
?要不是…If it were not for...（= were it not for...）
If it hadn't been for...（= had it not been for...）“要不是因為有……;如果不是……”
例
If it hadn't been for the determined captain,all the passengers on board wouldn't have been saved.
要不是船長的意志堅定，船上的旅客就不會得救。
?It is（high/about）time that +從句,從句謂語動詞為過去式或should+動詞原形（should通常不省略）“……早就該……”
例
I think it is high time that she made up her mind.
我想她該拿定主意了。
?would rather sb.did sth.
would rather后接從句,表示“寧愿某人做某事”,從句謂語動詞用過去時表示現(xiàn)在或將來的事情。
例
I would rather he were not present at the meeting tomorrow.
我倒希望他明天不要出席那個會議。
would rather sb.had done sth.
would rather后接從句,表示“寧愿某人已經做過某事（但實際上沒有做）”,從句謂語動詞用過去完成時表示過去的事情。
例
He would rather his son had agreed to take over his business.
他希望他的兒子答應接管他的生意。
