Answer:
answer the photo I could attach it
Answer:
May you please explain not trying to be mean or anything
The answer is: [A]: Idiom.
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The phrase: "castles in the air" is an idiom.
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Explanation: "Castles in the air", literally speaking, are impossible to exist or be created.
So, when used as an idiomatic phrase, it refers to events that cannot, or likely will not, be possible to achieve.
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The indefinite word in this sentence is "all'' because it is formed from a indefinite pronoun therefore it is a indefinite adjective.