enigmatically       
adverb uk/ˌen.ɪɡˈmæt.ɪ.kəl.i/ us/ˌen.ɪɡˈmæt̬.ɪ.kəl.i/
 费解地;难以捉摸地;神秘地
in a way that is mysterious and impossible to understand completely
  "Who was that?" "Just a man I know," she said enigmatically. “那是谁?”“只是一个我认识的人,”她神秘地说。 
 enigmatically beautiful artworks  神秘美丽的艺术品 
 See: enigmatic
 - More examples
- He walked along the train platform, enigmatically observing people.
- The film concerns a man who enigmatically vanishes on a beach, and his wife's efforts to find out what happened.
- He smiled enigmatically.