tread on air 与 walk on air 两者都是“非常高兴，得意扬扬，飘飘然”的意思，用于口语，常用进行时。

• Ever since Jane heard that she's been admitted to the university, she's been treading/walking on air .
  自从得知自己考上了大学，简天天快乐极了。
• The teacher's compliment left him walking/treading on air .
  老师的赞扬让他得意扬扬。