hadn't       
uk/ˈhæd.ənt/ us/ˈhæd.ənt/
 (had not的缩略形式)
short form of had not
  If you hadn't told him he would never have known. 如果你没有告诉他的话,他可能永远也不会知道。 
 - More examples
 - She was disappointed that they hadn't phoned.
 - Four years after he left college he still hadn't found a job.
 - The examiners failed him because he hadn't answered enough questions.
 - She looked as though she hadn't slept all night.
 - I'd have drowned if he hadn't been there to pull me out of the river.