Roughly stated, you are following the Liskov Substitution Principle if you can use any implementation of an abstraction in any place that accepts that abstraction.
粗略地说，如果你可以在任何接受抽象的地方使用那个抽象的任何实现，就是在遵循Liskov替换原则。
2
Each evolution takes place in a short time and is limited by the time box principle.
每一次进展发生得时间很短，并会受限于时间。
3
Django strictly observes the Don't Repeat Yourself (DRY) principle, whereby every distinct piece of code or data lives in only one place.
Django严格遵循Don ' t Repeat Yourself (DRY)原则，因此每个不同的代码片段或数据仅在一个位置上出现。