Final answer:
The sentence contains an adverbial phrase, 'for twenty minutes each day', which describes the verb 'wrote', indicating the duration of the writing activity.
Step-by-step explanation:
The sentence 'We wrote in our journals for twenty minutes each day' contains an adverbial phrase. An adverbial phrase provides information about the verb in a sentence, such as when, how, or where something happens. In this case, 'for twenty minutes each day' describes the duration of the action, which is writing in the journals, hence functioning as an adverb modifying the verb 'wrote'. It does not contain an adjectival or adverbial clause, as it does not have a subject and a verb, nor does it specify anything about a noun in the way an adjective would.