The best friend a man has in the world may turn against him and become his enemy.

一个人在世上最好的朋友会和他反目，成为他的敌人。

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The best friend a man has in this world may turn against him and become his enemy.

一个人在这个世界上最好的朋友都有可能背叛他，成为他的敌人。

youdao

Thee best friend a man has in this world may turn against him and become his enemy.

在这个世界上，一个人的好友可能与他做对、变成敌人；

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In other words, the PTO is forcing the patent owner to become his own worst enemy.

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