Answer:
The functional morphemes in this sentence are "he," "had," "an," "and," "a," "full," "of," and "book."
Functional morphemes are small units of language that have a specific grammatical or syntactical function in a sentence, but do not have a specific meaning on their own. In this sentence, the functional morphemes serve to indicate the subject of the sentence ("he"), the past tense of the verb ("had"), the indefinite article ("an" and "a"), the conjunction ("and"), the possessive determiner ("full"), and the preposition ("of"). These morphemes do not have a specific meaning on their own, but they are crucial for the correct grammatical structure and meaning of the sentence.