什么是让步状语从句

让步状语从句 引导让步状语从句的连词主要有以下这些：though, although, as; even if, even though; whether...or...; no matter+疑问词,疑问词-ever.下面对这些连词引导的让步状语从句作一说明.
（1）though, although表示“虽然,纵然”之意.
这两个连词意思大致相同,在一般情况下可以互换使用.在口语中,though较常使用,although比though正式,二者都可与yet, still或nevertheless连用,但不能与but连用.例如：
Alhough/Though he was worn out, (still) he kept on working. 虽然他已经精疲力竭了,但仍然继续工作.
Although/Though he is very old, (yet)he is quite strong. 他虽然年纪大了,身体还很健壮.
值得注意的是,although引导的让步状语从句位于主句之前的情况较多,though引导的让步状语从句可位于主句之前或主句之后.例如：
She passed the examination though she had not studied very hard. 她虽然不用功学习,考试却及格了.
（2）as, though表示“虽然……但是”,“纵使……”之意.
as引导的让步状语从句必须以部分倒装的形式出现,被倒装的部分可以是表语、状语或动词原形,though间或也用于这样的结构中,但although不可以这样用.例如：
Object as you may, I " ll go.(=Though/Although you may object, I " ll go.) 纵使你反对,我也要去.
Hard as/ though he works, he makes little progress. (=Though he works hard, he makes little progress.)尽管他学习很努力,但几乎没取得什么进步.
Child as/though he was, he knew what was the right thing to do.（=Though he was a child, he knew what was the right thing to do.）虽然他是一个孩子,但他知道该做什么.
Fast as you read, you can " t finish the book so soon. 纵然你读得快,你也不能这么快读完这本书.
（3）even if, even though 表示“即使……”,“纵使……”之意.
这两个复合连词的意思基本相同.它们常可互换使用,但意义有细微差别.even if引导的让步从句含有强烈的假定性,而even though引导让步状语从句时,是以从句的内容为先决条件的,也就是说,说话人肯定了从句的事实.例如：
We " ll make a trip even if/though the weather is bad. 即使天气不好,我们也要作一次旅行.
Even if he is poor, she loves him. (=He may be poor, yet she loves him.)即使他很穷,但她还是爱他.
Even though he is poor, she loves him. (=He is poor, yet she loves him. )尽管他很穷,但她还是爱她.
（4）whether...or...表示“不论是否……”,“不管是……还是……”之意.
由这一个复合连词引导的让步状语从句旨在说明正反两个方面的可能性都不会影响主句的意向或结果.例如：
You " ll have to attend the ceremony whether you " re free or busy. 不管你忙不忙,都要参加这个典礼.
Whether you believe it or not, it " s true.无论你是否相信,这都是真的.
（5）“no matter+疑问词”或“疑问词-ever”的含义为“……都……；不管……都……”,它们引导的让步状语从句可以互换.例如：
No matter what happened, he would not mind. (=Whatever happened, he would not mind.)无论发生了什么,他都不会介意的.
No matter who you are, you must keep the law.(=Whoever you are, you must keep the law.不管你是谁,你都要遵纪守法.
但“no matter+疑问词”结构只能引导让步状语从句,而“疑问词-ever”还可以引导名词性从句.例如：
Whatever(=No matter what)you say, I won " t believe you. (Whatever 引导让步状语从句)无论你说什么,我都不会相信你.
I " ll eat whatever(≠no matter what)you give me. (whatever引导宾语从句)你给我吃什么,我就吃什么.
Whoever comes will be welcome. (Whoever 引导主语从句) 不管谁来都受到欢迎.
此外,有时while也可以引导让步状语从句,但一般要位于句首.例如：
While I like the colour, I don " t like the shape.我虽然喜欢那颜色,但不喜欢那形状.
综上所述,我们可以看出,学习让步状语从句的关键是关联词的选用；其次,要注意的是由as引导的让步状语从句要用倒装语序.
让步状语从句表示：虽然,尽管,即使等概念,由although（尽管）, though（尽管）, however（无论怎样）, whatever（无论什么）, whoever（无论谁）, whomever（无论谁）, whichever（无论哪个）, whenever（无论何时）, wherever（无论哪里）, whether（是否）, no matter (who, what, where, when, etc) （无论……）, even if（即使）, even though（即使）等词引导.
如： We won”t be discouraged even if(=even though) we fail ten times.我们就是失败十次也不泄气.
It was an exciting game, though / although no goals were scored.那是一场精彩的球赛,尽管一个球都没进.(though, although不能与 but连用)
Whether you believe it or not, it”s true.不管你信不信,这是真的.
However (=No matter how) expensive it may be, I”ll take it.无论它有多贵,我也要买下它.
Don”t let them in, whoever(=no matter who) they are.不管他们是谁,别让他们进来.
No matter what I say or how I say it, he always thinks I”m wrong.无论我说什么或怎么说,他总认为是我错.
特别提醒
1.no matter
what（who,which,when,etc.）与whatever（whoever,whichever,whenever,etc.）的区别：
当引导让步状语从句时,两者相同,可以互换,但当引导名词性从句（主语从句,宾语从句,表语从句和同谓语从句）时则只能用whatever（whoever,whichever,whenever,etc）.如上面最后两个例句可改为：
e．g． However pure the water looks,I do not want to drink it.
I want to marry the man I love, no matter who he may be.
下面句字不能用no matter结构:
Whoever comes back firs is supposed to win the prize.(主语从句)
I am ready to do whatever you want me to .（宾语从句）
2. as 引导让步状语从句的用法：
引导让步状语从句时,as意为“虽然,尽管”,通常从句要倒装,倒装的方法是将从句的表语或状语放在as之前,而用though引导让步状语从句时句字则不必倒装（口语中也可倒装）.
e.g. Heavily as it was raining outside, they started out very early.
Young as he is, he knows a lot=Though he is young 或Young though he is, he….
他虽然年轻,但懂得很多.(though 也有这种用法,可以替换as,但although没有这种用法)
though还可以用作副词,放在句末.如：
It was hard work;; I enjoyed it, though=It was hard work, but I enjoyed it.那工作很苦,但是我喜欢干.
3.用though/although, as 引导让步状语从句时,句中不能用but表示转折语气.
不能说：Though he looks weak, but he is healthy.
而要说：Though he looks weak, he is healthy.
或者说：He looks weak, but he is healthy.
我自己认为让步就是存在一定条件下的说法.