快速答案
ir 侧重前往目的地；andar 侧重移动方式、交通手段或某人近来的状态。
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
ir
to go
Use ir for movement toward a destination or a planned trip.
andar
to walk, ride, or get around
Use andar for the way someone moves around or an activity repeated over time.
如何选择
- ir: Choose ir if the sentence points to movement toward a destination or a planned trip.
- andar: Choose andar if the sentence points to the way someone moves around or an activity repeated over time.
例句
Vou ao mercado.
I am going to the market.
Ando de ônibus todos os dias.
I take the bus every day.
常见误区
Andar does not always mean “walk.” With de plus transport, it means to get around by that means.
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 ir，一次用 andar。如果两个版本都可以，说明意思怎样变化。