Which sentence does not contain an adverb? They usually live in the southeastern United States and eat rabbits, rodents, and bir
ds. The eastern diamondback rattlesnake is the largest poisonous snake in the United States. Like many other rattlesnakes, they frequently make a buzzing sound with the rattles on their tails when they feel threatened. Eastern diamondbacks grow as long as eight feet, with the average length often being two to six feet.
"The eastern diamondback rattlesnake is the largest poisonous snake in the United States. "
This is because adverbs tend to describe another verb or adjective (how, when, where, how much, how often.) The other sentences use words that describe things as well as words like "usually" and "frequently", which are obvious adverbs.