Surveillance is the careful watching of someone, especially by an organization such as the police or the army.
例句
He was arrested after being kept under constant surveillance...在被连续监视了一段时间后,他被逮捕了。Police swooped on the home after a two-week surveillance operation...在两周的监视行动之后,警方突击搜查了那栋房子。
英汉词典释义
n.
盯梢, (对犯罪嫌疑人或可能发生犯罪的地方的)监视
The police have been keeping her under surveillance.警察一直把她置于监视之下。
英英词典释义
Noun
1. close observation of a person or group (usually by the police)