It was an unwritten law of the Mafia that nobody should talk to the police.黑手党有不成文的规定，就是任何人都不许跟警察交谈。Alice is accused of sinning against this unwritten law.爱丽斯被指责违反这条不成文法。I hope there's no unwritten law about what type of wine you should drink.我希望没有关于应该喝哪种葡萄酒的不成文的规定。