I thought she was acting foolishly, but I bit my tongue [=held my tongue] and didn't say anything.我觉得她的行为很愚蠢，但我忍住了，什么也没说。

“I hope he gets hurt.” “Bite your tongue! [=don't say that] That's a terrible thing to say!”“我希望他受伤。”“住嘴吧！那样说太不像话了！”