It's not only because walls have ears but also because it's not a virtue that we should never speaks ill of others behind their backs.
不仅是因为隔墙有耳，还因为这不是一种美德，所以我们才绝应该不在背后说他人坏话。
2
People who we thought to be our friends but we found out that they were talking behind our backs, or that they were operating to deceive us in some way.