漫不经心

例句：

1. 1. He was so busy that he couldn't pay attention to the meeting.
   他太忙了，以至于无法关注会议。
2. 2. She was so absorbed in her work that she didn't notice the time passing by.
   她全神贯注于工作，以至于没有注意到时间流逝。
3. 3. He was so careless that he forgot his keys at home.
   他太粗心了，把钥匙忘在家里了。