首先必须知道as引导让步状语从句：表语/状语（或动词原形或其他形式） as 从句，as意为：虽然…但是、尽管，通常从句要倒装。
例：Child as he is, he knows much about science.
尽管他是一个小孩，但他对科学了解得很多。
Rich as he is ， he is not happy.虽然他富有，但是却不快乐。
Heavily as it was raining outside， they started out very early.
虽然外面下着大雨，但是他们很早就出发了。
Angry as he was, he managed to speak calmly.
虽然他很生气，但是他讲话很平静。
Tired as I was, I tried to help them. 虽然我很累，我还是努力帮助他们。
Try as he would, he couldn’t open the door. 他试过多次了, 却仍打不开那门。
Search as they would, they would find nobody in the house. 无论怎样搜查，他们在房子里仍然没有找到一个人。
Hard as (though) they tried, they couldn’t make her change her mind. 尽管他们做了很大努力，却没法让她改变主意。
Boy as he was, he behaved like a girl. 他虽是个男孩，但举止却像个女孩。
解析说明：
as作“虽然…但是、尽管”解，引导让步状语从句时，必须将表语、状语或动词原形提到as前面。此时应注意以下考点：
一是若提前的表语是没有形容词修饰的单数可数名词，要省略不定冠词；
二是若提前的是动词原形(多为不及物动词)，与之连用的通常是may, might, will, would等，且这些词都要保留在原来的位置上(即主语后)；
三是在让步状语从句中though有时(多在口语)也可像as这样用倒装语序。如：
Happy as they were, there was something missing.
尽管他们很快乐，但总缺少点什么。
Try as he might (= however hard he tried) , he couldn't open the door.
他想尽了办法也没能打开门。
Object as/though 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。
Young as/though he is， he knows a lot = Though he is young，he knows a lot.
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）
倒装语序的as从句既可以表示让步，又可以表示原因，表原因是译为：由于、因为等，在引导表示原因的原因状语从句时不能用though或although来替换句型：
请看：
Tired as he was, we decided not to disturb him.由于他很疲劳，我们不去打扰他了。
Experienced as he is in contrast to his colleagues, he can deal with any difficult situation.
由于他跟同事们相比很有经验，所以他能对付任何困难的局面。
Unaccustomed as I am to public speaking, I beg your indulgence for my few inelegant works.由于我不习惯于发表演说，有些话讲得不大得体敬请谅解。
此时这个as不能替换为though或although的句型。大家明白了吗？可笑的是有些老师不明白这个理，就干脆说though引导的句子不可以倒装。
小结：as倒装语序有以下三种句型形式：
(1). 形容词或副词 as 主语 连系动词be或实义动词。例如：
Small as atoms are, they are made up of still smaller units.
尽管原子很小，但它们由更小的单位构成。
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。
Rich as he is, he never spends a cent on clothes.
虽然他很富有，但他从不花一分钱在衣服上。
Much as I admire his courage, I don’t think he acted wisely.
我虽然佩服他的勇气，但我认为他这样做是不聪明的。
Stupid as it sounds, Tom fell love with her at the first sight and believe everything she says. 虽然听起来很蠢，但汤姆对她一见钟情，相信她说的每一句话。
Much as I admire him, I don’t want to follow his way.
虽然我很钦佩他，但我不想走他的路。
(2). 名词 as 主语 连系动词be (注意句首的名词不带冠词)。例如：
Child as he is, he knows a lot.
尽管他是个孩子，但懂很多事情。
Boy as he was, he was chosen king.
尽管他还是个孩子，但却被立为国王。
Lover of towns as I am, I realize that I owe a debt to my early country life. 尽管我爱城市，但我知道，以往的乡村生活使我受益匪浅。
(3). 实义动词 as 主语 助动词[如果没有助动词，则要加上一个do(does或did)]。例如：
Try as he may, he never succeeds.
尽管他很努力，但总是不成功。
Change your mind as you will, you will gain no additional support.
即使你改变主意，你也不会得到另外的支持。
Try as he might, he could not solve that problem.
尽管他尽力了，他还是解决不了那个问题。
Raining hard as it was, Tom went out for a walk. 尽管雨下得很大，汤姆还是出去散步了。
Surrounded as we were by the enemy, we were not afraid at all. 我们虽然被敌人包围了，但一点也不害怕。
