有一位读者来信问：
(1)We suggested that we put off the meeting till next Monday.
在这一句中，put off 之前是否省去了should? TOEFL 例句中说不可加上should, 否则算错。应如何理解？
这里的确有一个英国英语与美国英语不尽相同的问题。在英国英语中，例（1）中put off 之前可用助动词should, 亦可不用，其意义不变。但在美国英语中，像例（1）这样的句子，一般只用现在虚拟式put off, 其前不加助动词 should。 TOEFL 即是以此标准进行考试的。但应指出，例 （1）用put off 也好，用should put off 也好，它们都是独立的虚拟时式，所以不存在put off 之前是否省去should 的问题。不少读者对should put off 这样的虚拟式比较熟悉，而对put off 这样的现在虚拟式似乎有点陌生，所以我们愿借此机会谈谈现在虚拟式的问题。
什么是现在虚拟式呢？ 简言之，现在虚拟式（present subjunctive)是一种独立的虚拟时式，它区别于过去虚拟式（如were）, 其形式与动词原形相同。这种虚拟式比较古老，常用在各种从句之中，如：
(2)It is best that he go .（用于主语从句）
(3)The idea is that the education for the oversixteens be improved . （用于表语从句）
(4)I desired that the action be postponed . （用于宾语从句，这里谓语动词虽是过去式 desired, 其后的从句仍须用虚拟式）
(5)If there be none, never mind it.（用于条件状语从句，比较文气，现已少用）
(6)It is high time that he go . （用于定语从句，现多用过去虚拟式went 或were going）
现在虚拟式也可用在独立句中，多表愿望，如：
(7)Long live the People's Republic of China!
(8)God forbid !
(9)The devil take you! （亦可认为省去首词 may）
有时还可引导一个独立句，在形式上与祈使句相似，如：
(10)Be it so.
(11)Let them take care what they say.
(12)Suffice it to say that we have been delayed by storms.
注意： 我们常用的please （请）本也是现在虚拟式，（现在已被唤作感叹词），如：
(13)Please forgive me, everybody.
上述结构还常用作时间状语或让步状语，如：
(14)She will be 18 years old come Easter. （用于时间状语）
(15)Home is home be it ever so homely. （用于让步状语）
有一些习语中的动词原形实际上也是现在虚拟式，如：
(16)Sink or swim , I shall undertake it. （sink 与swim 之后省去了主语I，是古时的让步状语从句结构）
同一位读者还提出一个颇为重要的问题。他举了这样一道小试题：
(17)_____, I would not have gone.
全句意谓“我要是你的话，当时是不会去的”。要求写上所缺的话填四个词。答案是 If I were you。但请问填作 Had I been you 行不行？ 为什么？
不行，这里必须填If I were you, 因为它已成为一种固定的说法。其中的were 不但不可改为had been, 也不可代之以不很正式的过去虚拟式was, 这正如固定说法as it were 中的were 不可改变一样。
山东的一位读者来信问：
(18)Some （ecologists）believe that without drastic measures Europe's lands and forests would one day become acidic waste lands.
这一句中的without drastic measures 起什么作用？
例（18）中的without drastic measures 是一短语，在句中用作条件状语，意谓“如不采取严厉措施”，所以其后的谓语动词用的是表结果的过去将来虚拟式would become。这种不用if 从句所表的条件叫作含蓄条件。除用介词短语表示含蓄条件外，还可以用其它词语表示含蓄条件，如：
(19)Ordinarily, they would have investigated the case immediately. （副词 ordinarily 表示含蓄条件）
(20)Horsewhipping would be too good for such a scoundrel. （名词horsewhipping 表示含蓄条件）
(21)Not to be moved by it would require a heart of stone. （不定式短语 not to be moved by it 表示含蓄条件）
(22)Anyone seeing them together might have been excused for taking her for Robbie's somewhat older sister. （分词短语seeing them together 表示含蓄条件）
(23)What would you think of my sister singing? （my sister singing 在此 = if my sister sang）
以上句子有的含蓄条件皆为非真实条件。含蓄条件也可以是真实条件，如：
(24)A little drink will work wonders in a cowardly man. （a little drink 表真实含蓄条件）
(25)Let's go. We'll be lucky to get there before dark. （to get there before dark 表真实含蓄条件）
有一位北京的读者问到it is important （essential, etc.）后接的主语从句是否必须用虚拟语气？ 可否用直陈语气？
如按语法规则讲，it is important （necessary, essential, natural, strange, etc.）后接的主语从句如不表事实而表主观态度，则皆应用虚拟语气，可是事实上，除在正式文体中外，直陈语气已不罕见，如：
(26)It's important that we are not drawn into the same group as Serbia and Herzegovina, because that will mean we'll have trouble getting to the semifinals.
(27)It was essential that she learned quickly.
这说明在当代英语中，或者说在现代英语中，确实有一种虚拟语气被代之以直接语气的趋问。这种趋向似乎也侵入了demand, suggest 等动词后接的宾语从句之中，如：
(28)She demands that Jacques goes on.
(29)Most of those surveyed suggested that the State makes legislation defining job change as a legitimate right.
这位读者还问：有人说在
(30)It's time we left.
这一句中只能用left, 对吗？
不对。下面的说法也都正确：
(31)It's time we leave .
(32)It's time we should leave .
(33)It's time we were leaving .
这位读者又问道：虚拟语气除用在上述修饰 time 的定语从句外，还可以用在别的定语从句中吗？
虚拟语气也可以用在其它定语从句之中，而且并不罕见，如：
(34)Any boy who should do that would be laughed at.
(35)A man might pass for insane who should see things as they are.
(36)Some scientists thought that the dust layers on the moon were so deep and loose that they might swallow up anyone who landed there.
(37)Most of the enterprises which were asked to donate did not dare to refuse for fear the units they annoyed would take revenge.
有一位中学教师来信要求解释下列句中的“would have+过去分词”：
(38)“The bomb would probably have destroyed the plane soon after takeoff,” police said.
(39)If you would have come sooner you could have helped us.
(40)I wouldn't have said that if I had thought it would have shocked her.
(41)I wouldn't have dreamed it.
(42)“My mother never considered her children's education,” said the man, who didn't have any schooling, “since she was not even sure if she could raise us. My father thought that if we could make our own living after growing up he would have done his duty.”
(43)— He had an accident last — when would it have been?
— About May.
(44)“Do you know how near the edge you are?” he rasped. “Look! One step beyond that stone and there'd have been no question of keeping you here.”
“would have+过去分词” 结构用法较多，而且也不都是虚拟时式，所以遇到它时需要进行具体分析。现按上述例句的顺序逐一分析如次：
例（38）中的would have destroyed 显然是我们常见到的表示与过去事实相反的过去将来完成虚拟式，其所在的主句表示结果，其条件从句大概是if it had not been discovered,被省去了。
例（39）中would have come 是虚拟式，但已古旧，应代之以 had come。
例（40）中的虚拟式would have shocked 可以代之以虚拟式would shock，二者可以通用，其意义亦无甚不同，但其着眼点却不一样。前者是从说话人说话时的角度看的，后者是从had thought 所表的时间看的。但须注意，后者如可能被理解为直陈语气时，则须用前者。
例（41）中的wouldn't have dreamed 的用法与例（40）中的would have shocked 相同，只不过它是否定结构而已。这里自然也可用虚拟式wouldn't dream，其与wouldn't have dreamed 的区别也是在于着眼点不同。
例（42）中的would have done 不是虚拟语气，而是直陈语气。换言之，would have done在此是过去将来完成时，用在谓语动词 thought 后接的间接引语that 从句中。过去将来完成时表示在过去将来某一时间以前发生的动作。这里that 从句中的过去将来某一时间即暗含在if从句之中。
例（43）中的 would have been 也不是虚拟时态。would 在此是一情态动词 （或叫做情态助动词），表示较大的可能性，相当于汉语“大概”。would have been 指过去，正如 might （could）have been 指过去一样。when would it have been 这一疑问句的意思是： 这大概是什么时候的事？
例（44）中’d have been 即=would have been。 按照一般教学用的语法规则，这里应用would be, 以表示与过去将来事实可能相反的虚拟结果。但这里却用了would have been。
据笔者所见，这种过去将来完成虚拟式似乎多用于美国英语中，而且并不鲜见，值得我们注意。其用这种虚拟式的原因可能有二： 一是美国英语中往往保存了一些古旧的表现法，而用过去将来完成虚拟式表示过去将来即是其中之一；二是这种虚拟式的虚拟性比较明显无误，而过去将来虚拟式则有被误解为直陈语气的可能。再举一例，供参考：
(45)She was a pretty baby. She would have grown up to be a beautiful woman. He wondered what her life would have been like. Would she have gotten married and had children? Or perhaps become an artist or a teacher or a business executive? Would she have been rich or poor? Happy or unhappy?（此例中的话皆是一位医生接生后的设想。省去的虚拟条件是“如果这个婴儿能成活的话”）
