I am of medium height 为什么这样要用of 没有of可以吗

为什He is of medium height为什么要of? she is medium height可以等于she is of medium height吗 Dave ( ) of medium height.are They are of medium height. He is of medium height.中为什么加of? he is of medium height.（划线部分提问）划线部分of medium hight 如果划线部分没有i is of medium height 还是 is medium height 要不要加上of 是I'm of medium height还是I‘m medium height如题 be of medium height 有事可以省略of吗?如：he is （）（）. 英语中He is of medium height. 能改成He is medium height .吗 可不可以说He is medium height ? 为什么He is medium build就可以去掉of呢?求助啊 _____?---she is of medium height.