It was a three-hour journey 中的hour为什么不加S,不是复数要加S的吗?

问题描述:

It was a three-hour journey 中的hour为什么不加S,不是复数要加S的吗?

It was a three-hour journey
多个形容词中间用【-】连接,都用单数的,这样【 three-hour 】直接看成一个完整的形容词
不加s的