快速答案
cada 强调群体中的每一个个体；todo 把成员视为整体，或表示完整的事物。
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
cada
each
Use cada for looking at members of a group one by one.
todo
every or the whole
Use todo for making a general statement about all members or one complete thing.
如何选择
- cada: Choose cada if the sentence points to looking at members of a group one by one.
- todo: Choose todo if the sentence points to making a general statement about all members or one complete thing.
例句
Cada pessoa tem um ingresso.
Each person has a ticket.
Todo mundo chegou.
Everyone arrived.
常见误区
Cada does not change to a plural form. Todo changes to toda, todos, or todas when the noun requires it.
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 cada，一次用 todo。如果两个版本都可以，说明意思怎样变化。