Question

"iron is not as coastly as gold " change into superlative degree​

Answer 1

gold is better than the iron

Answer 2

Answer:

Sorry but I think this sentence cannot be changed into superlative degree..

Explanation:

When we're comparing between two things in a sentence, we cannot make the sentence superlative. Because here we're saying iron is not costly means gold is more costly than iron (is). But we cannot say Gold is most costly metal or etc. because there are many metals who are more costly than gold.

Hope it helps you and you understand why this sentence cannot be changed into superlative.