快速答案
deixar 是日常的“让、留下”，含义较广；permitir 直接表示允许。
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
deixar
to let or leave
Use deixar for everyday permission, noninterference, or leaving something in a state or place.
permitir
to permit or allow
Use permitir for explicit authorization, especially in neutral or formal language.
如何选择
- deixar: Choose deixar if the sentence points to everyday permission, noninterference, or leaving something in a state or place.
- permitir: Choose permitir if the sentence points to explicit authorization, especially in neutral or formal language.
例句
Meus pais deixaram eu viajar.
My parents let me travel.
O regulamento não permite animais.
The rules do not allow animals.
常见误区
Because deixar is broader, deixei a porta aberta means “I left the door open,” not necessarily “I allowed the door to open.”
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 deixar，一次用 permitir。如果两个版本都可以，说明意思怎样变化。