hard-and-fast rule

The teacher said that there was a hard-and-fast rule against smoking in school.

教师说学校有严格的禁止吸烟的规定.

Finally, he writes his definitions, following the hard-and-fast rule that each definition must be based on what the quotations in front of him reveal about the meaning of the word.

最后词典编者写出每个义项的定义，在下定义时，编者必须遵守这样一条不容改变的铁的规则：那就是每个义项的定义编者必须根据摆在面前那些卡片上的例句所含有的该词的词义来写。

There is no hard-and-fast rule for doing this, but adopting a proper link sequence for dependent shared libraries should work most of the time.

关于这一点，没有一成不变的规则，不过，为相关的共享库采用适当的链接顺序大部分时候都会管用。

There's no hard-and-fast rule.

并无定规.

There is no hard-and-fast rule for the ratio because it depends on the queries involved.

对于这个比率，并没有什么严格的规则，因为这依赖于所涉及的查询。