长80米英文可以表达为"eighty meters long"或者"80 meters in length"。

关于这个表达的来源，需要先了解一下英文中表达长度的基本结构。在英文中，通常会使用形容词来表示长度，如"short," "long," "tall," "wide," "narrow"等。这些形容词可以用来修饰名词，例如"a short table," "a long road," "a tall building," "a wide river," "a narrow path"等。

当需要表达具体的长度时，可以使用"meter"这个单词，它是一个长度单位，在英文中翻译为"米"。在表示长度时，可以使用"meter"这个单词，例如"five meters," "ten meters," "twenty meters"等。

当需要表达长度时，可以使用"long"这个形容词，并在它后面加上"meter"这个单位，例如"a long meter"。

下面是一些英文例句和它们的中文翻译，希望对你有帮助：

The bridge is eighty meters long. (这座桥长80米。)
The snake is three meters long. (这条蛇长3米。)
The swimming pool is fifty meters in length. (这个游泳池长50米。)
The beach is two hundred meters long. (这个海滩长200米。)
The river is four kilometers long. (这条河长4公里。)