Final answer:
In the given sentence, the adverbial phrase is 'this term', which provides more information about when the prescribed action of a new teacher joining the school took place.
Step-by-step explanation:
In the sentence, 'A new teacher joined our school this term', the adverbial phrase is 'this term'. An adverbial phrase serves to provide more information about the verb in a sentence. In this case, 'this term' offers more information about when the action (the new teacher joined our school) took place. Adverbial phrases can also tell us where, why, or how an action occurred.
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