Design Patterns C#

using System;
public interface IEmployee {
    string Design();
    string StressTest();
    string Mechanical();
    string Performance();
}
public class ChiefDesignEngineer : IEmployee {
    public string Design() {
        return "Design ";
    }
    public string StressTest() {
        return "Stress Test";
    }
    public string Mechanical() {
        return "mechanical";
    }
    public string Performance() {
        return "performance";
    }
    public ChiefDesignEngineer() { ;}
}
public class ProxyChiefDesignEngineer : IEmployee {
    private ChiefDesignEngineer chief;
    public string Design() {
        return this.chief.Design();
    }
    public string StressTest() {
        return this.chief.StressTest();
    }
    public string Mechanical() {
        return "supplement to mechanical.";
    }
    public string Performance() {
        return "Performance for Chief Design Engineer";
    }
    public ProxyChiefDesignEngineer() {
        this.chief = new ChiefDesignEngineer();
    }
}
public class Client {
    static void Main(string[] args) {
        ProxyChiefDesignEngineer caProxyChief = new ProxyChiefDesignEngineer();
        Console.WriteLine(caProxyChief.StressTest());
        Console.WriteLine(caProxyChief.Performance());
        ProxyChiefDesignEngineer nyProxyChief = new ProxyChiefDesignEngineer();
        Console.WriteLine(nyProxyChief.Mechanical());
    }
}