He replied with a casual air.

他漫不经心地回答。

《新英汉大辞典》

I was wrong about it being a casual meeting.

我错认为那是一次非正式的会面。

《柯林斯英汉双解大词典》

She had a purposeful air, and it became evident that this was not a casual visit.

她一副志在必得的样子，显然这不是一次随意造访。

《柯林斯英汉双解大词典》

Professor Johnson suspects a strong link between the rise of instant and casual communication online and an increase in writing mistakes.

VOA: special.2010.01.28

So the three of us would have a casual and unstructured conversation with the president in what direction he wanna to go.

所以我们三个会随便地,没有系统地聊一下,总统想说什么就说什么。

普林斯顿公开课 - 国际座谈会课程节选

In another situation, you could be at a casual lunch setting with friends, eating pizza.

在另一种情况中，你可能正与朋友一起吃一顿便饭，你们吃的是披萨。

Is it okay 课堂 - SpeakingMax英语口语达人

The abuse admitted by Ms. Lerner can't be dismissed in a casual apology on a casual Friday as no big deal.

WSJ: Review & Outlook: The IRS Targets Conservatives

Like all dystopias, the power of this play is that it shows how mundane and casual a descent into the abyss might look, and with what familiar bureaucratic language.

BBC: Alcopops, racism and financial dystopia

Andy Gerrard, a West Devon Methodist, said for many farmers the rain had gone from a casual joke to a serious threat to their livelihoods.

BBC: Devon farmers 'despair' over rain and poor harvest