A hard-and-fast rule is clear, definite, and meant to be used every time — you are not supposed to bend it. The phrase you will hear most is the negative one: “There is no hard-and-fast rule,” meaning there is no single rule that fits every case. It feels a little formal, and it almost always sits in front of rule, line, or distinction.

A hard-and-fast rule一條 hard-and-fast 的規則 is clear清楚、definite明確，and meant to be used every time而且每一次都要照用——you你 are not supposed to bend it不應該去彎折它。you will hear most你最常聽到的 The phrase說法 is the negative one是否定的那句：“There is no hard-and-fast rule,”沒有硬性規定，meaning意思是 there is no沒有 fits every case能套進每一種情況的 single rule單一一條規則。It它 feels a little formal感覺稍微正式，and it而它 almost always幾乎總是 rule, line, or distinction在 rule、line 或 distinction 這幾個字 sits in front of前面出現。

Though actually it did not start with rules. It was first used in the 1860s of a ship on shore, stuck firm — “hard” on the ground and “fast” in the old sense of “fixed, not moving,” the same fast as in fasten, not the “quick” fast. From a ship that cannot move, it became a rule that cannot move.

Though actually不過其實 it它 did not start with rules一開始不是講規則的。It它 in the 1860s最早在 1860 年代 was first used被拿來講 of a ship on shore一艘擱在岸上、stuck firm卡死不動的船——“hard” on the ground是「結結實實」壓在地上，and “fast” in the old sense of是舊義的 “fixed, not moving,”「固定、不動」，as in fasten和 fasten 裡的 the same fast同一個 fast，not the “quick” fast不是「快」的那個 fast。From a ship that cannot move從一艘動不了的船，it became它變成了 a rule that cannot move一條動不了的規則。