hard-and-fast rules

There are no hard-and-fast rules of procedure for securing intelligence by infiltration through enemy lines.

没有严格的规定越过敌人防线获得情报的步骤。

There are no hard-and-fast rules for success.

通往成功没有什么一成不变的规则。

His parents have no hard-and-fast rules about how late he can stay out.

他的父母对他在外可以逗留多晚并没有严格的规定。

Given the difficulty of judging brand names isolated from performance, are there any hard-and-fast rules for naming a service company?

考虑到不从表现来判断品牌好坏的难处，有无专用而奏效的被用来指定一家服务公司的惯例？

There are no hard-and-fast rules for getting a job in television.

干电视这一行没有一成不变的规则。

Keep in mind that not all recommendations are appropriate for all situations, and that they are offered as guidelines, not hard-and-fast rules.

务必记住，并非所有的建议都适合于所有情形，并且这些建议是作为指导原则而不是作为硬性规则来提供的。