Definition: to secretly try to discover information about a person, country, etc. Level: C1
该特工被派往国外，负责对军事设施进行间谍活动。
The agent was sent abroad to ___spy on military installations.
该软件旨在防止竞争对手窥探我们的研究。
The software is designed to prevent competitors from ___spying on our research.
我觉得我弟弟在试图打探妈妈把我们的礼物藏哪儿了。
I think my little brother is trying to ___spy on where Mom hid our presents.
