Understanding the Concept of טירחא יתירה (Excessive Tircha, Major Exertion) on Shabbos;
understanding the Concept of מבטל כלי מהיכנו (Nullifying a Vessel from Its Usage);
דבר דבר (Dabair Davar): If Something Is Not Allowed to Be Done on Shabbos, One Could Not Say They Will Be Doing It During...