vigilance

英文解釋：

名詞 vigilance:

1. the process of paying close and continuous attention
   同義詞：watchfulness, wakefulness, alertness
2. vigilant attentiveness
   同義詞：watchfulness, weather eye

英文造句：

1. The price of liberty is eternal vigilance.
   自由的代價是永久提高警惕。
2. You cannot afford to relax your vigilance for a moment.
   警惕性是萬萬不可放鬆的。
3. In spite of vigilance a polar bear escape from the zoo.
   儘管警戒很嚴，北極熊還是逃出了動物園。
4. Police's vigilance was eventually rewarded.
   警方時時警戒終有所獲。