c#新手遇到错误求救。。


using System;namespace p290_21
{
    public  delegate void Del();
    public class BigCat
    {
        public void Cry()
        {
            Console.WriteLine("肥猫看见老鼠后大叫！");
        }
 
    }
    public class Host
    {
        public static void awake()
        {
            Console.WriteLine("主人醒了!");
        }
 
    }
    public class Mouse
    {
        public static void awake()
        {
            Console.WriteLine("老鼠受到惊吓!");
        }
 
    }
    class Program
    {
        static void Main(string[] args)
        {
            Del d = null;
            Host h = new Host();
            Mouse m = new Mouse();
            BigCat bc = new BigCat();
            Console.WriteLine("肥猫是否发现老鼠？");
            string str;
            str = Console.ReadLine();
            if (str[0] == 'y')
            { 
                bc.Cry();
                //Del d = null;
                
                d += Host.awake();
                d += Mouse.awake();
                d();
 
            }
           
                    }
    }
}
调用委托出错啊。。
新手看不懂。。求救。。
------ 已启动生成: 项目: p290_21, 配置: Debug Any CPU ------
C:\WINDOWS\Microsoft.NET\Framework\v3.5\Csc.exe /noconfig /nowarn:1701,1702 /errorreport:prompt /warn:4 /define:DEBUG;TRACE /reference:"C:\Program Files\Reference Assemblies\Microsoft\Framework\v3.5\System.Core.dll" /reference:"C:\Program Files\Reference Assemblies\Microsoft\Framework\v3.5\System.Data.DataSetExtensions.dll" /reference:C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\System.Data.dll /reference:C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\System.dll /reference:C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\System.Xml.dll /reference:"C:\Program Files\Reference Assemblies\Microsoft\Framework\v3.5\System.Xml.Linq.dll" /debug+ /debug:full /filealign:512 /optimize- /out:obj\Debug\p290_21.exe /target:exe Program.cs Properties\AssemblyInfo.cs
C:\Documents and Settings\Administrator\桌面\代码\vs\9.24作业\home_work\p290_21\Program.cs(46,17): 错误 CS0019: 运算符“+=”无法应用于“p290_21.Del”和“void”类型的操作数
C:\Documents and Settings\Administrator\桌面\代码\vs\9.24作业\home_work\p290_21\Program.cs(46,22): 错误 CS0029: 无法将类型“void”隐式转换为“p290_21.Del”
C:\Documents and Settings\Administrator\桌面\代码\vs\9.24作业\home_work\p290_21\Program.cs(47,17): 错误 CS0019: 运算符“+=”无法应用于“p290_21.Del”和“void”类型的操作数
C:\Documents and Settings\Administrator\桌面\代码\vs\9.24作业\home_work\p290_21\Program.cs(47,22): 错误 CS0029: 无法将类型“void”隐式转换为“p290_21.Del”编译完成 -- 4 个错误，0 个警告
========== 生成: 成功 0 个，失败 1 个，最新 0 个，跳过 0 个 ==========