App 클래스 using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; namespace LearnDotnet { internal class App { //생성자 메서드 public App() { //업캐스팅 IAttackable marine = new Marine(); marine.Attack(); //다운캐스팅 Marine m = (Marine)marine; m.StimPack(); } } } Marine 클래스 using System; using System.Collections.Generic; using System.Linq; using System..