是副词.简单的判断法就是看它能否放到宾语的后面.介词是不可以的. put on the coat 可以变成 put the coat on turn off the light --- turn the light off 这里的 on,off 是副词. walk on the spot jump off the wall 不能这样变换,是介词 又,代词作宾语时,副词只能摆在后面 put on the coat ,put it on take out the books,take them out 代词作宾语时,介词只能摆在前面 jump off the wall ,jump off it.