The farmer told the students they were welcome to come back at anytime!
Answer: "It's a dog" and "Who's that?"
Explanation:
The comma is putting together and shortening 'it is' and 'who is'.
Scout characterizes Boo as a petty criminal and a "malevolent phantom." Jem describes his neighbor as a monstrous figure, six-and-a-half feet tall with bloodstained hands. Dill must imagine Boo based on the descriptions his friends provide him.