leave 如果表示离开学校,是及物动词,后面不接任何介词.
leave如果表示动身去学校,是不及物动词,后面必须接介词for.
用法如下,共楼主参考
leave for 是出发至某处
如:He left for Beijing yesterday.
leave sth for sb 是把什么留给什么人
如：She left these flowers for you.
leave sb for sb 是离开什么人去和什么人在一起
如：He left his wife for a young lady.
leave sth to do sth 是指为做某事离开某处
如：He left her house to catch the last bus.
leave sb doing sth 是让某人单独做某事
如：Don't leave your children playing with fire.