选D
考的是让步状语从句
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.