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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Answer:
This phrase is a metaphor "The earth is the cup of the sun, That filleth at morning" it is stating that the Earth is like a cup that in the morning will be filled by sunlight.
Answer:
In the space provided, write whether the verb in sentence is active voice or passive voice. Since the second century B.C., Indian women have worn saris.