条件句概念用法

A. 【英语语法：新概念】if引导的条件句（三种情况都要讲出来）

楼主，你说的是不是虚拟语气呀？
含有if条件句的虚拟语气的构成如下：
1） 对现在虚拟： 条件句：一般过去时， 主句：could/would/should/ought to/might+动词原形
例：if he were here now, we could have a meeting. 如果现在他在这儿，我们就可以开会了。(注意用的是he were。he was也可以，不过虚拟语气里be动词规范的用法还是多以were的形式出现 )
2）对过去虚拟： 条件句： 过去完成时，主句：could/would/should/ought to/might have done
例： if he had taken my advice, he shouldn't have failed in the exam. 如果他听从我的建议，他考试就不会不及格。
3）对将来虚拟： 条件句：（1）were to do (2) should do (3)一般过去时 主句：could/would/should/ought to/might +动词原形
例： If i had time/were to have time/should have time, I would visit my parents tomorrow. 如果我明天有时间，我就去看望我的父母

B. 请教英语条件句的用法

这是虚拟用法，表明“如果你现在到了北京的话，你就不可能找不到新东方学校”。
但是你现在不在新东方，
你现在到达新东方这件事与现实是相反的，所以用if sb +过去时

C. allow条件句的用法

concent courtesy empower grant permissibility permission permit
acknowledge accept acceptability

D. 条件状语从句的用法以及注意事项！

不建议死记规则，语言讲究的是感觉，多读多背，感觉自然出来

E. 条件状语从句的条件状语用法

条件状语从句的用法是：

1. if 表示正面的条件， 意为“如果”； unless (=if not) 表示负面的条件， 意为“除非， 如果不”。例如： If you ask him, he will help you. 如果你请求他， 他会帮助你。// If you had come a few minutes earlier, you would have met him. 要是你早来几分钟就碰到他了。(本例句属于第8章中介绍过的以虚拟语气表示非真实条件句的情况。) // He is sure to come unless he has some urgent business. 他一定会来， 除非他有急事。

2. in case， on condition that， providing， provided (that)， supposing， suppose (that)等词汇意思相近， 指“假如， 假使， 在……条件下”(比if更为书面化)。例如： In case he comes, let me know. 如果他来的话， 告诉我一声。// I shall give you my dictionary on condition that you return it tomorrow. 我将把我的字典给你， 如果你明天要还的话。 // I will go, providing/provided (that) my expenses are paid. 只要我的费用有人付， 我就去。 // Suppose/Supposing (that) he does not come, what shall we do? 他要是不来， 我们该怎么办？

3. as long as (=so long as) 表示充分必要条件， 引导语气强烈的条件状语从句时， 意为“只要”。例如： I will cooperate as long as I am notified on time. 只要及时告诉我， 我就会合作。 // You may use the book so long as you will return it on time. 只要你准时还， 你就可以借这本书。

F. 条件状语从句中的连词用法

条件状语从句
通常由以下连词引导：if, unless, on condition that, suppose, in case(如果，万一), as /so long as(只要)等 如：
①If you are thirsty, water far away can’t help you.
远水不解近渴。
②So long as we do not divorce ourselves from the masses, we are certain to be victorious.
只要我们不脱离群众，我们就一定会胜利。
③You can’t expect the reception to be clear unless the radio set is properly tuned it.
如果不把收音机调好，你不可能指望收到清晰的播音。
④Suppose we can’t get the necessary equipment, what shall we do?
假设我们弄不到必要的设备，那我们怎么办？
⑤We’ll let you use the room on condition that you keep it clean and tidy.
我们可以让你们用这个房间，如果你们能保持整洁的话。
⑥Send us a message in case you have any difficulty.
万一有什么困难请给我们一个信。

unless作连词，表示“如果不”，“除非”，在意义上等于if…not, 在有些场合主要是指真实条件句，它引导的肯定式的条件状语从句可以和if引导的否定式的条件状语从句互换。

如：Unless you change your mind, I won’t be able to help you.
= If you don’t change your mind, I won’t be able to help you.
除非你改变你的想法，否则我不能帮助你。

unless不可用于假想的事情，因此，当if…not引导非真实条件状语从句时，一般不可改用unless.
如：
If she weren’t so silly, she would understand.
如果她不那么傻，她就会懂了。

G. 如何学习条件状语从句（条件状语的用法，结构，句型装换）

这句话很正常啊,就是一个普通的if引导的条件状从..
你参考下资料吧..

真实条件句用于陈述语气，假设的情况可能发生，其中 if 是如果的意思。

时态关系

句型： 条件从句 主句

一般现在时 shall/will + 动词原形

If he comes, he will bring his violin.

典型例题

The volleyball match will be put off if it ___.

A. will rain B. rains C. rained D. is rained

答案B。真实条件句主句为将来时，从句用一般现在时。

注意：

1） 在真实条件句中，主句不能用be going to表示将来，该用shall, will.

(错) If you leave now, you are never going to regret it.

(对) If you leave now, you will never regret it.

2） 表示真理时，主句谓语动词便不用shall (will) +动词原形，而直接用一般现在时的动词形式。

16.2 非真实条件句

1）时态：可以表示过去，现在和将来的情况。它的基本特点是时态退后。

a. 同现在事实相反的假设。

句型 ： 条件从句 主句

一般过去时 should( would) +动词原形

If they were here, they would help you.

b. 表示于过去事实相反的假设。

句型： 条件从句 主句

过去完成时 should(would) have+ 过去分词

If she had worked harder, she would have succeeded.

The rice would not have been burnt if you had been more careful.

If my lawyer had been here last Saturday, he would have prevented me from going.

If he had come yesterday, I should / would have told him about it.

含义：He did not come yesterday, so I did not tell him about it.

If he had not been ill and missed many classes, he would have made greater progress.

含义： He was ill and missed many lessons, so he did not make greater progress.

c. 表示对将来的假想

句型： 条件从句 主句

一般过去时 should+ 动词原形

were+ 不定式 would + 动词原形

should+ 动词原形

If you succeeded, everything would be all right.

If you should succeed, everything would be all right.

If you were to succeed, everything would be all right.

16.3 混合条件句
主句与从句的动作发生在不同的时间，这时主，从句谓语动词的虚拟语气形式因时间不同而不同，这叫做混合条件句。

If you had asked him yesterday, you would know what to do now.

（从句与过去事实相反，主句与现在事实相反。）

If it had rained last night (过去), it would be very cold today (现在).

16.4 虚拟条件句的倒装
虚拟条件句的从句部分如果含有were, should, 或had, 可将if省略，再把were, should或had 移到从句句首，实行倒装。

Were they here now, they could help us.

=If they were here now, they could help us.

Had you come earlier, you would have met him

=If you had come earlier, you would have met him.

Should it rain, the crops would be saved.

=Were it to rain, the crops would be saved.

注意：

在虚拟语气的从句中，动词’be’的过去时态一律用"were"，不用was， 即在从句中be用were代替。

If I were you, I would go to look for him.
如果我是你，就会去找他。

If he were here, everything would be all right.
如果他在这儿，一切都会好的。

典型例题

_____ to do the work, I should do it some other day.

A. If were I B. I were C. Were I D. Was I

答案C. 在虚拟条件状语中如果有were, should, had这三个词，通常将if省略，主语提前, 变成 were, should, had +主语的形式。但要注意，在虚拟条件状语从句中，省略连词的倒装形式的句首不能用动词的缩略形式。如我们可说 Were I not to do., 而不能说 Weren’t I to do.

16.5 特殊的虚拟语气词：should

1） It is demanded / necessary / a pity + that…结构中的主语从句的谓语动词要用should 加动词原形， should 可省略。

句型：
(1)suggested

It is (2)important that…+ (should) do

(3) a pity

(1)suggested, ordered, proposed, required, demanded, requested, insisted； + (should) do

(2)important, necessary, natural, strange

a pity, a shame, no wonder

(3)It is suggested that we (should) hold a meeting next week.

It is necessary that he (should) come to our meeting tomorrow.

2）在宾语从句中的应用

在表示命令、建议、要求等一类动词后面的从句中。

order, suggest, propose, require, demand, request, insist, command, insist + (should) do

I suggest that we (should) hold a meeting next week.

He insisted that he (should ) be sent there.

注意： 如suggest, insist不表示"建议" 或"坚持要某人做某事时"，即它们用于其本意"暗示、表明"、"坚持认为"时，宾语从句用陈述语气。

The guard at gate insisted that everybody obey the rules.

判断改错:

（错） You pale face suggests that you (should) be ill.

(对) Your pale face suggests that you are ill.

(错) I insisted that you ( should) be wrong.

(对) I insisted that you were wrong.

3）在表语从句，同位语从句中的应用

在suggestion, proposal, idea, plan, order, advice等名词后面的表语从句、同位语从句中要用虚拟语气，即（should）+动词原形。

My idea is that we (should) get more people to attend the conference.

I make a proposal that we (should) hold a meeting next week.

H. 英语中条件状语从句的用法

条件状语从句表示主句的动作发生的条件、假想、推测或意愿。用连词
if,
unless
和起连接作用的短语
except
that;
in
case
that;
on
condition
that;
provided/providing
that;
so/as
long
as;
suppose/supposing
that
引导。
用法:
1.从句表示的条件客观上是现实的，常用陈述语气，如:
If
the
stamp
is
torn,
it's
no
good
for
my
collection.如果邮票是破的，那我收集起来就没有用了。
Suppose
all
the
doors
are
locked,
how
will
you
get
into
the
house?
假如所有的门都锁上了，你怎么会进到这所房子呢?
2.从句表示的条件同事实相违背或不可能实现，通常用虚拟语气。如:
If
I
were
captain
of
a
ship,
I
would
take
you
on
a
voyage
round
the
world.如果我是一艘轮船的船长，我将带你航海环游世界。
注意事项:
1.用一般现在时表示将来时。
The
meeting
will
be
held
out
of
doors
unless
it
rains.除非下雨，大会将在户外举行
2.用选择完成时替代将来完成时。
If
I
have
made
a
mistake,
I
will
try
to
remedy
it.如果我犯了错误，我将会努力改正
3.will用在真实条件状语从句中是情态动词，表示意愿或决心，而不是单纯表示将来。
I
will
tell
you
if
you
will
come
on
Friday.如果你愿意星期五来，我将告诉你。
还有其他一些情况，你暂时用不到，以后自己多注意。

I. if引导的真实条件句含义、结构、用法、例句，详细。

if +主谓宾，抄主谓宾。大概是这么一袭个结构 例如 if you are late for school,you will be punished by the theacher.if 引领条件句，表示在此条件成立时，会发生的状况。if 后可以跟现在完成时 一般现在时 一般过去式。用什么根据后面的主句来决定。其实时态很好选择 ，只要你分得清过去、现在和将来。例如上面一句 可以翻译成：如果你迟到了，你将会受到老师的惩罚。很明显，迟到是在受惩罚之前 而且是还未发生的事。再给你举个例子，if you finished your homework,you would not have been punished by the theacher today.如果你昨晚做完作业了，今天就不会被老师罚了。这是对过去的假设，多联系 多体会 你会很容易运用这些语句的 good luck every day!

J. 真实条件句和非真实条件句的含义及两者在用法上的区别

你好复 很高兴为你解答制 请看网址http://ke..com/view/26751.htm#1 http://ke..com/view/630435.htm
真实条件句实际上就是条件状语从句，这个是真实的，有可能发生
但虚拟语气则是不可能实现的，例如：如果我有100万，我将周游世界，这就是虚拟语气，又叫非真实条件句 详细组成看我给的网址 谢谢