gang up
phrasal verb with gang verb uk/ɡæŋ/ us/ɡæŋ/
disapproving
（为了反对某人）结伙，联合起来，拉帮结派
to unite as a group against someone
They all ganged up to try and get him to change his decision. 他们联合起来，试图使他改变决定。
The whole class ganged up against/on her because she was the teacher's pet. 因为老师偏爱她，所以整个班上的学生都合伙跟她作对。