快速答案
教的人 ensina，学的人 aprende。
可靠的方法是先判断这个词在句子里的功能，再翻译。
每个词的作用
ensinar
to teach
Use ensinar for giving knowledge or showing someone how to do something.
aprender
to learn
Use aprender for receiving and developing knowledge or a skill.
如何选择
- ensinar: Choose ensinar if the sentence points to giving knowledge or showing someone how to do something.
- aprender: Choose aprender if the sentence points to receiving and developing knowledge or a skill.
例句
Ela ensina português.
She teaches Portuguese.
Eu aprendo português.
I learn Portuguese.
常见误区
The direction matters. Ensinar sends knowledge to someone, while aprender brings it into the learner.
放到语境中练习
从你的真实生活中选一个句子，写两遍：一次用 ensinar，一次用 aprender。如果两个版本都可以，说明意思怎样变化。