The students began whispering and giggling once they saw the teacher close the book. The adverb clause once they saw the teacher close the book modifies

The adverb clause modifies the verb phrase "began whispering and goggling".

Explanation:

An adverb clause is a group of words or clauses that modifies a verb, an adjective, or an adverb in a sentence. This means that an adverb clause will change or qualify the verb, adverb, or adjective in a sentence.

The adverb clause in the given sentence is "once they saw the teacher close the book". And this adverb clause modifies the verb phrase "began whispering and giggling". The verb phrase contains the main verb and the words accompanying it, the verb dependents, thereby making it a phrase.

Thus, the adverb clause modifies the verb phrase.

began whispering and goggling

Explanation:

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the answer is slaves

douglas was a slave who turned into a statesman and he refused to celebrate the 4th of july until all slaves were emancipated or set free.

answer: do you have any options

explanation: