as 引导的让步状语从句多用倒装句,即把在从句中做表语的名词、形容词或谓语动词中的主要动词放在句首.当作表语用的单数可数名词位于句首时,名词前的不定冠词要省略.例如：
　　Pretty as she is,she is not clever.
　　Try as he would,he might fail again.
　　Clever as he is,he doesn’t study hard.
　　Child as she is,she knows a lot.