快速答案
sair 表示主语离开；deixar 通常带被留下或被允许的对象。
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
sair
to leave or go out
Use sair for the subject moving away from a place.
deixar
to leave something or let
Use deixar for putting someone or something behind, or allowing an action.
如何选择
- sair: Choose sair if the sentence points to the subject moving away from a place.
- deixar: Choose deixar if the sentence points to putting someone or something behind, or allowing an action.
例句
Saí de casa às sete.
I left home at seven.
Deixei as chaves na mesa.
I left the keys on the table.
常见误区
Do not say deixei de casa for “I left home.” That phrase would need another structure and can suggest stopping an activity.
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 sair，一次用 deixar。如果两个版本都可以，说明意思怎样变化。