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也可用于这样的结构中,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
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）.