hard and fast   (TTS發音)

not to be broken or changed；fixed；strict嚴格的；非遵守不可的；不能變動的

    It's a hard and fast rule；everyone must obey it. 這是個嚴格的規則，大家都必須服從。

    The traffic regulations must be observed in a hard and fast way；any negligence would cause an accident. 交通規則必須嚴格遵守，任何疏忽都會造成事故。

    The teacher said that there was a hard and fast rule against smoking in the school. 老師說校方規定不準抽煙，任何人不允許違反這條規定。