dead zone         
noun [ C ] uk/ˈded ˌzəʊn/ us/ˈded ˌzoʊn/
 无信号区(移动电话因无信号而无法使用)
a place where a mobile phone does not work because there is no signal
  无事发生的时间(或地点)
a place or time in which nothing happens
  The village is a dead zone for many young people. 对许多年轻人来说,这村落是与世隔绝的。