Answer :
To learn calculus is challenging for me.
challenging on behalf of me is a prepositional phrases
Prepositional phrases :
A phrase may be a group of words consisting of a preposition, its object, and any words that modify the thing . Most of the time, a phrase modifies a verb or a noun. These two sorts of prepositional phrases are called adverbial phrases and adjectival phrases, respectively
A phrase starts with a preposition and ends with a noun or a pronoun. Examples of prepositional phrases are “in our house” and “between friends” and “since the war.
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