unsuccessful       
adjective uk/ˌʌn.səkˈses.fəl/ us/ˌʌn.səkˈses.fəl/
B2 不成功的,失败的;落空的
not achieving the hoped for result; not successful
  They made several unsuccessful attempts to reach the men. 他们试着好几次联络那几个男人,结果都落了空。 
 His application was unsuccessful. 他的申请失败了。 
 Synonyms: abortive failed
Opposite: successful
 - More examples
 - Her bid for re-election was unsuccessful.
 - Attempts to trace the whereabouts of a man seen leaving the scene of the crime have so far been unsuccessful.
 - Our firm stands to lose a lot of money if the deal is unsuccessful.
 - We are sorry to inform you that your application has been unsuccessful.
 - We have been unsuccessful in finding a replacement.