as引导的让步状语从句有什么特殊用法?

as可引导让步状语从句,表示“虽然、尽管”,但要用部分倒装结构,形式如下：
1.形容词 + as + 主语 + 系动词.如：
Tired as he is,he offers to help me.
尽管他已经很累了,他还是主动提出帮助我.
2.过去分词 + as + 主语 + 系动词.如：
Well-written as the book is,the author is not satisfied and prepared to revise it.
尽管这本书写得很好,作者还是不满意并打算修改它.
3.名词 + as + 主语 + 系动词.如：
Student as he is,he does not study hard.
他虽然是个学生,却不努力学习.
4.副词 + as + 主语 + 谓语部分.如：
Much as I admire his courage,I don’t think he acted wisely.
我虽然崇拜他的勇气,但我认为他这样做是不明智的.
5.动词原形 + as + 主语 + 谓语的另一部分（情态动词或助动词may,might,will,would等）.如：
Try as you will,you won’t be able to persuade him.
不管你怎么努力,你都说服不了他.
【考例1】 _____,I have never seen anyone who’s as capable as John.（上海2001）
A.As long as I have traveled
B.Now that I have traveled so much
C.Much as I have traveled
D.As I have traveled so much
【考例2】 _____,Carolina couldn’t get the door open.（广东2005）
A.Try as she might B.As she might try
C.She might as try D.Might she as try
Key:1.C 2.A