prep.关于，至于
adj.适当的，恰好
adv.顺便说一说，恰好

Apropos of your question, I've done some research on the topic.
关于你的问题，我做了一些研究。
Let's change the subject; apropos, have you seen the latest movie?"
让我们换个话题；顺便说一句，你看过最近的电影吗？
Apropos of nothing, do you know how to play chess?"
闲聊一下，你知道怎么下棋吗？
The weather is an eternal topic of conversation, apropos.
天气是永恒的聊天主题，这是真的。
His sudden arrival was most apropos, as we were just discussing him.
他的突然到来非常适时，因为我们刚刚在谈论他。
Her timely arrival was indeed apropos for the celebration.
她的适时出现确实适合庆祝活动。
Apropos of the matter, I must apologize for my tardiness.
关于这件事，我必须为我的迟到道歉。
I believe his suggestion is quite apropos for our current situation.
我认为他的建议非常适合我们当前的情况。
The discussion turned to fashion, apropos of the gala event tomorrow.
谈话转到了时尚，因为明天有个盛会。
In a way, her experience mirrors the topic we were discussing, apropos.
在某种意义上，她的经历恰好符合我们刚才讨论的主题。