를 알고

know … (with the object marked by 를)

→ 를
phrase Rare #29,089
know … (with the object marked by 를) 를 marks the object of 알고 (“know”) and is used after a vowel; 을 is used after a consonant. 알고 있다 is a common way to express “know.”
KO: 저는 그 캐릭터를 알고 있어요.
EN: I know that character.

당신은 그 꼬마를 알고?

Do you know that kid?

— 피케이: 별에서 온 얼간이 (2014)