hem someone in
phrasal verb with hem verb [ T ] uk/hem/ us/hem/ -mm-
包围，限制（某人）
to surround someone and prevent them from moving or doing what they want to do
When they reached Trafalgar Square, the demonstrators were hemmed in by the police. 当他们到达特拉法加广场时，示威者们已被警方包围起来了。