To know (how to): ~ㄹ/을 줄 알다 By placing ~ㄹ/을 줄 알다 after a verb, you can indicate that one “knows how” to do that action. For example: 각도를 잴 줄 알아요 = I know how to measure the angle 저는 그것을 할 줄 알아요 = I know how to do that 자전거를 타다 means "ride a bicycle" 자전거(를) 탈 줄 알아요? means "Do you know how to ride a bicycle?" 자전거는 탈 줄 알아요? means "(I know that you cannot ride something). Do you know how to ride a bicycle?" 자전거도 탈 줄 알아요? means "(I know that you can ride something). Do you also know how to ride a bicycle?"