alert

• They must be constantly on the alert for the enemy .
  他们必须随时注意敌人。
• At this stage they sat straight and alert .
  此刻，他们正警觉地、笔挺地坐着。
• Old jolyon was on the alert at once .
  老乔里恩立刻警觉起来。
• That had alerted him, worried him secretly .
  这就提醒了他，使他暗暗上了心事。
• Had walden alerted the police yet ?
  沃尔登通知警察了吗？
• I've alerted the police up there .
  我已提醒那里的警察。
• He had been painfully alert .
  他一直兢兢业业小心在意。
• Her fears had always been on the alert for an upheaval .
  她日夜提心吊胆，严防突变。
• The sentries were all on the alert .
  哨兵们都警戒着。
• Our forces are normally in various states of alert .
  我们的部队通常处于不同的战备状态。