Hello, everybody! Can you help me with form 대로, please? :)
I'm interested in the meaning "extremely".
For example, if I'm not mistaken, the sentence "My friend bought an extremely old book." can be translated as "내 친구는 낡을 대로 낡은 책을 샀어요."
However, can we translate the sentence "I was extremely tired." as "저는 피곤할 대로 피곤했어요."?
Thank you very much! :)

Question

Hello, everybody! Can you help me with form 대로, please? :)
I'm interested in the meaning "extremely". 
For example, if I'm not mistaken, the sentence "My friend bought an extremely old book." can be translated as "내 친구는 낡을 대로 낡은 책을 샀어요." 
However, can we translate the sentence "I was extremely tired." as "저는 피곤할 대로 피곤했어요."? 
Thank you very much! :)

Answer

Adj + (으)ㄹ 대로 Adj pattern means "as Adj as it can be", where Adj has negative meaning.

e.g.
낡을 대로 낡은 책(O) the book which is as worn as it can be
좋을 대로 좋은 날씨(X)

I was extremely tired.
저는 피곤할 대로 피곤했어요. is grammatically correct but it is a rarely used.
저는 지칠 대로 지쳤어요. is more natural and commonly used.