hurt是“受伤”,老师说是用被动的.但是我又看到“my leg hurts",也有“I was hurt",还有”hu

hurt作为不及物动词时,表示“感到疼痛”,对应你上面的例子“my leg hurts”,就是“我腿疼”的意思.
hurt作为及物动词时,表示“（使）疼痛,受伤”,对应你上面的例子“hurt oneself”.
至于“I was hurt”,有人把此处的hurt作为形容词,就像《牛津高阶英汉双解词典》中,把hurt的形容词这个词性单独列出来,举的例子是“None of the passengers were badly hurt”.我觉得既然hurt作为及物动词时有“使受伤”的意思,那么把“I was hurt”理解成hurt的被动语态也未尝不可啊