sum of class

• 类的和

sum of class的用法和样例：

例句

1. Similarly, if a base and its derived types all need access to another class, that class must specifically grant access to the base and each derived class.
   同样，如果基类和派生类都需要访问另一个类，那个类必须特地将访问权限授予基类的和每一个派生类。