Here are the answers to your questions based on Dylan Thomas's poem “Do Not Go Gentle Into That Good Night”:
Question 1: In this poem, what is the first line called, in poetic terms?
Answer: first refrain
Question 2: What is the relationship between the second lines of each stanza?
Answer: They repeat.
Question 3: Which answer choice correctly defines refrain?
Answer: a line that repeats
Question 4: What is a villanelle?
Answer: a type of poem that uses three-line stanzas and two refrains
Question 5: What is the rhyme scheme of these stanzas?
(assuming the question refers to the overall poem, "Do Not Go Gentle Into That Good Night")
Answer: aba aba
Please check the specific line entries in the poem if required, as some interpretations could vary depending on context.