快速答案
a par 表示了解情况；ao par 是表示价值相等的专业术语。
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
a par
informed or aware
Use a par for being up to date with facts, a subject, or a situation.
ao par
at par or equal in value
Use ao par for financial parity, especially equal face and market value or equal exchange value.
如何选择
- a par: Choose a par if the sentence points to being up to date with facts, a subject, or a situation.
- ao par: Choose ao par if the sentence points to financial parity, especially equal face and market value or equal exchange value.
例句
Mantenha a equipe a par das mudanças.
Keep the team informed about the changes.
Os títulos foram negociados ao par.
The bonds were traded at par.
常见误区
For “aware of the news,” never add the article o: estar a par, not estar ao par.
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 a par，一次用 ao par。如果两个版本都可以，说明意思怎样变化。