A monkey has learned to turn on the lights,play a recorder when she is told to.最后为什么要加to

问题描述:

A monkey has learned to turn on the lights,play a recorder when she is told to.最后为什么要加to
A monkey has learned to turn on the lights,play a recorder when she is told to.末尾的to可以省略掉吗?tell是及物动词为啥要加上to呢?
原句为A three-year-old monkey named Helen has learned to 15 on and off the light,use a recorder and open doors and windows when he is told to.

这是一个省略的说法,应该是be told to do sth.被告知做某事.首先谢谢你的慷慨解答!但是省略的部分是什么呢?learn.... 其实就是前面提到的。