Birds of a feather flock together; people of the same kind tend to gather together; often used to describe those with similar interests or bad habits associating with each other.
小明发现，班里那些喜欢玩魔术的同学总是聚在一起，真是物以群分啊
Xiao Ming noticed that the students in the class who liked playing magic tricks always gathered together; truly, birds of a feather flock together.
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