Behind someone’s back: 在某人背后，背着某人，背地里。
我们不应该在背后说别人坏话：
We shouldn’t talk behind someone’s back.
你背着我偷吃巧克力！
You are eating chocolate behind my back.
他经常背地里说他老板的坏话：
He often speaks ill of his boss behind his back. Speak ill of sb, 说某人坏话的意思
在成为一个优秀的人之前先学会做一个勇敢的人
