Final answer:
Classical melodies typically have two phrases of equal length, forming a balanced and symmetrical structure that is easy to recognize and follow.
Step-by-step explanation:
Classical melodies are known for their distinctive structure, often adhering to compositional forms that were standardized during the Classical period. When discussing the structure of classical melodies in terms of their phrases, the most common layout would typically be two phrases of equal length. This balanced structure, known as binary or balanced phrase structure, allows for a clear and easily recognizable melody which often follows a pattern of statement and response or question and answer.