Which sentence does not contain an adverb? They usually live in the southeastern United States and eat rabbits, rodents, and birds. 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 answer is:

"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.

yes the first one is correct .

the pronoun reference replaces a noun, but you have to make sure there's no room for confusion.

in the first sentence "her" could be referring to shely or to the sister. the answer there is "shelly called her sister and told her about the new baby."

in the second sentence "it" could be referring to the roof or the floor. the answer there is "since the roof leaks on the family room floor, we need to repair the roof."