Tricky sentence

已经到了测试脚本开发的收尾阶段，为了保证测试脚本没有bug，整整一天都要用来运行QTP脚本。QTP运行的时候不能随便打搅，只好看书了。Sigh，谁让我只有可怜的一台机器呢。
最近正在复习有效软件测试<Effective.Software.Testing.50.Specific.Ways.to.Improve.Your.Testing>，打算再好好看一遍。经典就是经典，每次看都有新的体会。

刚刚看到前言第二段就看到一个比较Tricky的句子：
Knowledge of what constitutes a successful end-to-end testing effort is typically
gained through experience.The realization that a testing program could have been
much more effective had certain tasks been performed earlier in the project life
cycle is a valuable lesson.Of course, at that point, it's usually too late for the
current project to benefit from the experience.
细看之下才明白，原来说的是：
The realization ... is valuable lesson - 认识到...是有价值的教训；
A testing program could have been much more effective had certain tasks been performed earlier in the project life cycle - 如果在项目生命周期中某些任务越早完成，测试工作可能就会更加有效。还是虚拟语气的；
即有从句又有虚拟语气，看来作者不仅技术功力深厚，语言表达能力也很强啊。