快速答案
isentar 常正式免除税费或要求；eximir 解除责任、过错或义务。
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
isentar
to exempt
Use isentar for formally freeing someone from a tax, fee, requirement, or rule.
eximir
to release from responsibility
Use eximir for freeing someone from blame, duty, liability, or an obligation.
如何选择
- isentar: Choose isentar if the sentence points to formally freeing someone from a tax, fee, requirement, or rule.
- eximir: Choose eximir if the sentence points to freeing someone from blame, duty, liability, or an obligation.
例句
A lei isenta pequenas empresas da taxa.
The law exempts small businesses from the fee.
O cargo não o exime de responsabilidade.
The position does not release him from responsibility.
常见误区
They overlap with duties, but their strongest collocations differ: isenção fiscal and eximir-se de responsabilidade.
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 isentar，一次用 eximir。如果两个版本都可以，说明意思怎样变化。