Final answer:
The word 'soaring' is used as an adjective to describe the eagle's movement.
Step-by-step explanation:
In the sentence 'A soaring eagle is slowly flying across the sky', the word 'soaring' is used as an adjective. Adjectives describe or modify nouns and pronouns. In this case, 'soaring' is describing the noun 'eagle' by indicating how the eagle is moving.
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