I think even if you're in a chair, and you're sitting up straight with good posture, maybe hands on knees.

哪怕只是坐在椅子上，坐直并保持良好姿势，也许双手放在两膝上。

普林斯顿公开课 - 人性课程节选

First I go over the physical posture you should have because when you're sitting like we usually sit on the round cushion or the floor, re free of contact with people usually both your knees and your butt are for the kneeling.

首先理顺应有的身体姿势,因为打坐时,像我们常会坐在圆坐垫,或地板上，你要确定自己身旁不要有人，you，make，sure，you‘,通常两膝和臀部都要注意,都要碰到地面。

普林斯顿公开课 - 人性课程节选