Me podeis ayudar con la traducción de la expresión "to come in threes"? El contexto sería:
"- Larry's failed his exams, Amy's got chicken pox. Whatever next?
- Oh dear! They say these things come in threes, you know."
There is a folk belief that bad luck always happens three times and then stops for a while. So when, for example, we hear of one plane crash and then a second, we wait anxiously for the third and then believe there will be no more bad luck for a while. To "come in threes" means to happen three times.