4

说明：  由于“易语言.飞扬”还未完全成型，在此过程中如果有所改动，教材也会相应的改动，但是对于面向对象的编程来说，基本上是不会变的，因此本书作者才有信心将面向对象的编程方法写出来
(As the " easy language. Flying" has not yet fully formed, in this process is subject to change if the teaching materials will be modified accordingly, but for object-oriented programming, basically will not change, so the author of this book have confidence in the method of object-oriented programming will write)