I'm looking for a shirt for my dad.

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Does 'for my dad' modify 'shirt' or 'looking'?

Is 'for my dad' an adjective phrase or an adverbial phrase?

It modifies shirt, so is an adjective phrase.

The other fellow here is mistaken. If you were looking for your dad (who was missing), it would be adverbial, modifying "looking." In this case, it modifies shirt.

To determine whether "for my dad" modifies "shirt" or "looking," we need to understand the role of the phrase in the sentence.

In the sentence, "I'm looking for a shirt for my dad," the phrase "for my dad" provides additional information about the purpose or recipient of the shirt. It clarifies that the shirt is intended for the speaker's dad.

In terms of classification, "for my dad" is an adverbial phrase. Adverbial phrases typically modify verbs, adjectives, or other adverbs. In this case, it modifies the verb "looking" by specifying the purpose of the action, indicating "looking" for whom the shirt is intended.

So, to answer your question:
- "For my dad" modifies the verb "looking."
- "For my dad" is an adverbial phrase.