on/from the sidelines idiom
旁观；不参与
If you are on the sidelines or do something from the sidelines, you are not actively involved in something.
Women have been on the political sidelines for too long - we must now work towards getting into power. 女性在政治上旁观已久——我们必须努力争取权力。
She could only watch from the sidelines as her brother's health deteriorated. 她只能眼睁睁地看着弟弟的身体垮下去。