Take another look at the sentence:

Until the Weavers arrived home at 5 p.m., the clock ticked, the refrigerator hummed, and the dog snoring in the otherwise quiet house.

When you list grammatical items, you must use parallel structure. Here, the clock ticked and the refrigerator hummed are both short main clauses, but the dog snoring ... is a noun phrase modified by a participle phrase, thus wrecking the parallelism.

To fix the sentence, change the dog snoring to the dog snored.

Go to the next sentence.

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