Firing Chuck was a stupid thing to do, but it's too late to ask him to come back.Fue una estupidez haber despedido a Chuck, pero ya es muy tarde para pedirle que regrese.
b.
Una frase idiomatica cuyo significado no es deducible si se traduce palabra por palabra.
Do NOT stick that knife in the toaster while it's still plugged in. That would be a stupid thing to do.NO metas ese cuchillo al tostador mientras esté enchufado. El hacer eso es algo estúpido.
You put diesel in the tank? That was a stupid thing to do! Now we're going to have to get the car towed.¿Le echaste diésel al tanque? ¡Pero qué idiota eres! Ahora vamos a tener que llamar a una grúa.