全校在大礼堂集合。 The whole school (was) assembled in the main hall.
会议在星期二和星期四於大礼堂举行。 The meetings are on Tuesdays and Thursdays in the main hall.
那个大礼堂比这个大一倍。 That auditorium is as large again as this.
边座,楼座剧院或大礼堂中为了增加座席,而从后面或侧墙突出的具有倾斜地板的上面部分 An upper section, often with a sloping floor, projecting from the rear or side walls of a theater or an auditorium to provide additional seating.