question: warn:warning
choices.label: A B C D
choices.text: back and forth:come back coming:come payment:pay boil:boiled water
explanation: "warn" is a verb, and "warning" is a noun. "back and forth" is an adverb, not a verb, and "come back" is a verb, not a noun. "come" is a verb, not a noun. "payment" is a noun, not a verb, and "pay" is a verb, not a noun. "boil" is a verb, and "boiled water" is a noun.
relation: warning warn R3.3