英语翻译She is always running down her friends behind their back

un down
1.撞倒
The liner ran down a fishing-boat during the dense fog.
在浓雾中,客轮撞翻了一条渔船.
2.追寻
They are running down a criminal.
他们正在追缉一名罪犯.
3.诋毁
Uncle George is always running down the government.
乔治叔叔总是诋毁政府.
The man's always running me down.
那人老是说我的坏话.
4.耗损;用坏
Billy ran down my truck when he used it last summer.
去年夏天,比利用坏了我的卡车.
在这里取第三个意思~诋毁~
译为她总是在背后诋毁她的朋友,她很快就会没有任何朋友.