nonchalant

尽管面试很重要，他还是以一副漫不经心的样子走了进来。

Despite the important interview, he walked in with a ___nonchalant attitude.

他对新车上的深深划痕表现得惊人地无所谓。

He was surprisingly ___nonchalant about the deep scratch on his new car.

她用满不在乎的耸肩回答了教授提出的一道最难的题。

She answered the professor's toughest question with a ___nonchalant shrug.