Every day, Mozilla developers write code that is merged into a common code repository (mozilla-central) and every day that code is compiled so as to create a pre-release version of Firefox based on this code for testing purposes - this is what we call a Nightly build. Once this code matures, it is merged into stabilization repositories (Beta) where that code will be polished until we reach a level of quality that allows us to ship a new final release version of Firefox to hundreds of millions of people. This development process used to ship a new version of Firefox every 5 to 8 weeks is called the Train Model.
每天，Mozilla 开发人员编写合并到公共代码库（mozilla-central）的代码，并且每天编译代码以便基于此代码创建 Firefox 的预发布版本以用于测试目的 - 这就是我们所说的 Nightly 构建。一旦这段代码成熟，它就会被合并到稳定存储库（Beta）中，在那里代码将被不断修改，直到我们达到一定的质量水平，使我们能够向数亿人发布新的最终版本的 Firefox。每 5 到 8 周发布一个新版本 Firefox 的开发过程称为“火车模型”。