surveillance of variation of virus

例句：

1. 1. The police areconducting surveillance on the suspect'smovements.
   警方正在对嫌疑人的行踪进行监控。
2. 2. The government is under surveillance byinternational agencies.
   政府正受到国际机构的监控。
3. 3.The scientist was under surveillance for possible espionage activities.
   科学家因可能的间谍活动而受到监控。