英語六級語法精析之虛擬語氣
1.主從句謂語動詞的時態
***1***掌握主從句謂語動詞的規範搭配:
如：If the doctor had been available, the child could not have died.
There is a real possibility that these animals could be frightened, should there be a sudden loud noise.
***2***區分主從句表示的不同時間概念：
主從句謂語動詞所指時間不同，這叫做錯綜時間條件句，動詞形式應根據實際情況來調整。如：
Had it not been for the timely investment from the general public, our company would not be so thriving as it is.
***主句與現在事實相反，從句與過去事實相反***
Had Paul received six more votes in the last election, he would be our chairman now.
***主句與現在事實相反，從句與過去事實相反***
***3***識別事實和假設混合句：
Your math instructor would have been happy to give you a make-up examination had you gone and explained that your parents were ill at the time. ***句子前半部分為假設情況，而“父母病了”是事實*** I would have gone to visit him in the hospital had it been at all possible, but I was fully occupied the whole of last week. ***前半部分為假設，後半部分是事實***
2.名詞性從句的虛擬形式
名詞性從句是指賓語從句、主語從句、表語從句和同位語從句。從句的謂語動詞需用***should+***動詞原形表示虛擬。考生應熟悉：
***1***下列動詞做謂語時，that賓語從句中的動詞用虛擬形式：
desire, advise, recommend, command, direct, order, ask, demand, request, require, insist, maintain, move, propose, prefer, urge, vote。如：
In the past men generally preferred that their wives work in the home. I move that he be discharged for his serious mistake.
***2***下列形容詞和分詞做表語或補語時，that主語從句中動詞用虛擬形式：
advisable, desirable, insistent, preferable, urgent, appropriate, compulsory, crucial, essential, imperative, important, necessary, obligatory, possible, probable, proper, vital, advised, arranged, commanded, demanded, desired, ordered, proposed, recommended, requested, required, suggested。如： The board deem it urgent that these files should be printed right away. It is essential that all these figures be checked twice.
***3***下列名詞接同位語從句或表語從句時，從句中動詞用虛擬形式：
insistence, preference, recommendation, suggestion, proposal, motion, desire, requirement, request, order, necessity, importance, regulation, rule, resolution, understanding。如：
John Wagner’s most enduring contribution to the study of Afro-American poetry is his insistence that it be analyzed in a religious, as well as worldly, frame of reference.
They keep telling us it is of utmost importance that our representative be sent to the conference on schedule.
3.含蓄虛擬條件句的謂語動詞形式
含蓄虛擬語氣是指假設條件不通過if從句表達，而是暗含在其他結構中。考生應熟悉：
***1***連詞but, but that, or, or else;副詞otherwise, unfortunately等表示轉折假設。如：
A safety analysis would have identified the target as a potential danger. Unfortunately, it was never done. Victor obviously doesn’t know what’s happened; otherwise he wouldn’t have made such a stupid remark.
***2***介詞短語暗含假設條件，常用的有：without, but for, under more favorable conditions等。如：
But for the English examination I would have gone to the concert last Sunday.
***3***intended/meant/hoped/wished/plann或was/were +不定式完成式或had intended/meant/planned/hoped/wished +不定式一般式暗示虛擬語氣。如：
I intended to have called on you, but I was busy at that time.
***4***情態動詞完成式暗示虛擬語氣。如：
I should have called to make an airline reservation, but I didn’t.
4.常用虛擬形式的句型
***1***從句中動詞用過去式或過去完成式表示虛擬的句型：
would rather would as soon as though suppose… had rather would sooner as if supposing… If only… It is ***high*** time that…***從句中動詞只用過去式*** 如：
His wife would rather they didn’t talk about the matter any more.
If I were in a movie, then it would be about time that I buried my head in my hands for a cry.
***2***If it were not for… ***與現在事實相反***、If it had not been for… ***與過去事實相反*** 相當於but for。如：
If it had not been for his help ***= but for his help***, we would not have succeeded.
***3***If only…謂語動詞視情況選用適當的形式。如：
If only the committee would approve the regulations and put them into effect as soon as possible.
***4***lest/for fear that/in case 從句謂語用***should+***動詞原形。如：
The mad man was put in the soft-padded cell lest he injure himself.
***5***whether…or…有時謂語用be的原形，引導讓步虛擬從句，這種用法經常採用倒裝結構。如：
Church as we use the word refers to all religious institutions, be they Christian, Islamic, Buddhist, Jewish, and so on.