(1) 在正式文体中，as可用来表示“虽然”(although)，接倒装语序；though也可以这样用；均表示一种很强的对比。although不接倒装语序。

• Cold as it was, we went out to skate on the lake. (Although it was so cold, we went out...)
  虽然天气很冷，我们还是出去到湖上滑了冰。
• Tired as I was, I settled down to work as soon as I arrived. (Although I was very...)
  虽然我很疲劳，但我一到就着手干了起来。
• Bravely though they fought, they had no chance of winning.
  虽然他们战斗得很勇敢，他们也没有取胜的可能。

 (2) 有时，as也可以用这种结构表示“因为”(because)。

• Tired as she was, I decided not to disturb her.
  由于她很疲劳，我决定不去打扰她。