请问这句英文如何理解？

老外有时也是乱用的

应为All I have to do is to learn Engilish.
或All I have to do is learning Engilish.
All I have to do后要加名词性的东西。

to learn 吧

is和learn都是动词哈
英语两个动词是不可以连用的
所以learn不能用原形
要么就用介词短语to learn Engilish
要么就接名词短语learning Engilish