prey upon
phrasal verbprey on/upon somebody/something
(of an animal or a bird 兽或鸟 to hunt and kill another animal for food 捕食；猎获 Hawks prey on rodents and small birds. 鹰捕食啮齿动物和小鸟。
to harm somebody who is weaker than you, or make use of them in a dishonest way to get what you want 欺凌，坑骗，敲诈（弱者）