快速答案
cela 指牢房等封闭房间；sela 指马鞍。
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
cela
cell or small monastic room
Use cela for a confined room in a prison, convent, or monastery.
sela
saddle
Use sela for the seat fastened to a horse or another riding animal.
如何选择
- cela: Choose cela if the sentence points to a confined room in a prison, convent, or monastery.
- sela: Choose sela if the sentence points to the seat fastened to a horse or another riding animal.
例句
O detento foi levado para a cela.
The detainee was taken to the cell.
A sela foi colocada no cavalo.
The saddle was placed on the horse.
常见误区
The words sound alike in varieties that merge initial s and soft c. Their semantic fields never overlap.
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 cela，一次用 sela。如果两个版本都可以，说明意思怎样变化。