Precast is mainly a building word.

Precast這個字主要是a building word建築業用語。

Precast concrete has already been poured into a shape — a wall, a beam, a stair, a panel — in a factory or yard, left to go hard, and only then taken to the building site. Workers lift the pieces into place instead of pouring wet concrete into a mould on the site itself.

Precast concrete預鑄混凝土has already been poured into a shape已經先被灌進模子做成形狀——a wall, a beam, a stair, a panel牆、梁、樓梯、板——in a factory or yard在工廠或工地外的場地，left to go hard等它變硬，and only then taken to the building site才被運到工地。Workers工人lift the pieces into place把做好的組件吊裝定位，instead of而不是pouring wet concrete into a mould on the site itself在工地現場把濕的混凝土灌進模子裡。

People also use precast as a noun for one of those ready pieces, and as a verb: to precast a panel is to make it that way. Though actually, the idea is not only concrete; you can precast other materials in the same spirit, but in ordinary talk it almost always means concrete.

People也有人也把use precast as a noun precast當名詞用，指做好的其中一個組件，and as a verb也當動詞用：to precast a panel預鑄一塊板就是is to make it that way用這種方式做出它。Though actually不過事實上，the idea is not only concrete這概念不只用在混凝土；you can precast other materials in the same spirit其他材料也可以用同樣方式先做好，but在日常說法裡in ordinary talk it almost always means concrete幾乎都是指混凝土。

It sounds technical, not fancy. Builders like it because the weather on site matters less, and the shapes can be made more carefully. The everyday opposite is concrete cast in place, poured where it will live.

It sounds technical, not fancy這個字聽起來很技術性，不是花俏的用語。Builders like it建商喜歡這種做法because因為the weather on site matters less工地天氣影響變小，and the shapes can be made more carefully形狀也能做得更精細。The everyday opposite日常說法裡相反的是concrete cast in place現場澆置的混凝土，poured where it will live就是直接在最終要用的地方澆灌。

Do not hear “cast” here as the people in a film; this cast is the old making-sense: to pour something into a mould and let it take that shape.

Do not hear千萬別把「cast」here as the people in a film這裡的cast聽成電影裡的「卡司」（演員陣容）；this cast這裡的cast is the old making-sense是比較老的用法：to pour something into a mould把東西灌進模子裡and let it take that shape讓它定型。