c# - 公共(public)密封类SqlConnection:DbConnection，ICloneable

请帮助我理解以下内容：

public sealed class SqlConnection : DbConnection, ICloneable {...}

上节课我有两个疑问
在c中不可能有多重继承（我们可以通过接口实现）。但是这里dbconnection不是一个接口，那么它是如何支持多重继承的呢？
iclonable是一个接口。它有一个名为object clone（）的方法。但是在sqlconnection类中，该方法没有实现。怎么可能？
请帮助我理解这一点

最佳答案

这里没有多重继承。您可以从一个类继承并实现多个接口。这里，DBConnection是一个类，IClonable是一个interface
iclonable声明为Explicit Interface，这意味着您不能直接从类实例访问它，但必须显式转换为接口类型
例子

interface IDimensions
{
     float Length();
     float Width();
}

class Box : IDimensions
{
     float lengthInches;
     float widthInches;

     public Box(float length, float width)
     {
        lengthInches = length;
        widthInches = width;
     }

     // Explicit interface member implementation:
     float IDimensions.Length()
     {
        return lengthInches;
     }

    // Explicit interface member implementation:
    float IDimensions.Width()
    {
       return widthInches;
    }

 public static void Main()
 {
      // Declare a class instance "myBox":
      Box myBox = new Box(30.0f, 20.0f);

      // Declare an interface instance "myDimensions":
      IDimensions myDimensions = (IDimensions) myBox;

      // Print out the dimensions of the box:
      /* The following commented lines would produce   compilation
       errors because they try to access an explicitly implemented
       interface member from a class instance:                   */

      //System.Console.WriteLine("Length: {0}", myBox.Length());
    //System.Console.WriteLine("Width: {0}", myBox.Width());

    /* Print out the dimensions of the box by calling the methods
     from an instance of the interface:                         */
    System.Console.WriteLine("Length: {0}", myDimensions.Length());
    System.Console.WriteLine("Width: {0}", myDimensions.Width());
    }
 }