MulticastDelegate定义：

[Serializable]
public abstract class MulticastDelegate : Delegate
{
    // Fields
    private MulticastDelegate _prev;

    // Methods
    protected MulticastDelegate(object target, string method) : base(target, method)
    {
    }

    protected MulticastDelegate(Type target, string method) : base(target, method)
    {
    }

。。。

Delegate的定义；

Serializable, ClassInterface(ClassInterfaceType.AutoDual)]
public abstract class Delegate : ICloneable, ISerializable
{
    // Fields
    private RuntimeMethodInfo _method;
    private IntPtr _methodPtr;
    private IntPtr _methodPtrAux;
    private object _target;

    // Methods
    private Delegate()
    {
        this._method = null;
        this._methodPtrAux = IntPtr.Zero;
    }

    protected Delegate(object target, string method)
    {
        this._method = null;
        this._methodPtrAux = IntPtr.Zero;
        if (target == null)
        {
            throw new ArgumentNullException("target");
        }
        if (method == null)
        {
            throw new ArgumentNullException("method");
        }
        this.InternalCreate(target, method, false);
    }

    protected Delegate(Type target, string method)
    {
        this._method = null;
        this._methodPtrAux = IntPtr.Zero;
        if (target == null)
        {
            throw new ArgumentNullException("target");
        }
        if (!(target is RuntimeType))
        {
            throw new ArgumentException(Environment.GetResourceString("Argument_MustBeRuntimeType"), "target");
        }
        if (method == null)
        {
            throw new ArgumentNullException("method");
        }
        this.InternalCreateStatic((RuntimeType) target, method);
    }

 。。。

但是：

public delegate void Feedback(System.Object value);

private void FeedbackToConsole(System.Object value)

{

　　Console.WriteLine("Processing {0}",value);

}

调用：

Set.ProcessingItem(

　　new Set.Feedback((new Program()).FeedbackToConsole)

);

问题是：Delegate和MulticastDelegate都没有单个参数的构造函数（单个参数会出异常），却可以正常执行，搞不懂啊？