php __get()方法？

Question

面向对象中， __get()和 __set() 方法怎么处理多个变量function __get($xm1,$nl1,$xl1){return ($this->$xm1);return ($this->$nl1);return ($this->$xl1);}报错Method ren1::__get() must take exactly 1 argument in。。。分开写成三段也报错，只留一段可以执行