名词观察，侦探，间谍活动

1. 观察：Esperanto 世界语 | espial 观察 | espiegle 爱戏谑的

2. 侦探/间谍活动/观察：espensive /费用浩大的/昂贵的/ | espial /侦探/间谍活动/观察/ | espionage /谍/间谍组织/间谍活动/

noun

1. the act of detecting something
    catching sight of something

    Synonym: detectioncatchingspyingspotting