사 (sa) means, “I buy” or “buy it” in the intimate politeness level, and you can say 사요 (sayo) to be more polite. Look up the word 사다 (sada) in the dictionary. In a sentence, you can put the word for what you are buying in front of this verb. With a rising tone at the end, you can use it as a question, and when the sentence ends in a plain tone, it can be a plain sentence or an imperative, telling someone else to buy something.
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