unpremeditated [ˌʌnprɪˈmɛdɪˌtetɪd]

例句:

• This happy event--supposing it to be such--could only have occurred at an unpremeditated moment.
  这件愉快的事情——就算它愉快——只能发生在毫无预谋的时刻。
  
• The unpremeditated crime that Picasso commits to oneself is downhearted, should destroy copperplate depict almost.
  毕加索对自己犯的过失闷闷不乐, 几乎要将铜版刻画一毁了之.
  
• She still looks quite smart, but in an unpremeditated, careless way.sssss J. le Carr&eacusc;
  来自J. Osborne