e.g. Heavily as it was raining outside, they started out very early.

　　　　Young as he is, he knows a lot=Though he is young 或Young though he is, he….

　　　　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)

　　　　though还可以用作副词，放在句末。如：

　　　　It was hard work;; I enjoyed it, though=It was hard work, but I enjoyed it.那工作很苦，但是我喜欢干。

　　　　3.用though/although, as 引导让步状语从句时，句中不能用but表示转折语气。

　　　　不能说：Though he looks weak, but he is healthy.

　　　　而要说：Though he looks weak, he is healthy.

　　　　或者说：He looks weak, but he is healthy.

　　　　我自己认为让步就是存在一定条件下的说法.