할 줄 알다 is not always "can do" - Korean Q&A
The meaning of the sentence "그 사람이 영어 할 줄 알았어요." can change depending on the intonation and the context. Hyunwoo explains how this happens by giving your various intonation examples.
Free audio lesson on -줄 알다: https://talktomeinkorean.com/lessons/l6l27
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