.net 运算符重载 ==, ！=, Equals

我已经过了question次了

我明白，要落实==、!=、Equals().

public class BOX
{
    double height, length, breadth;

    // this is first one '=='
    public static bool operator== (BOX obj1, BOX obj2)
    {
        return (obj1.length == obj2.length 
                    && obj1.breadth == obj2.breadth 
                    && obj1.height == obj2.height);
    }

    // this is second one '!='
    public static bool operator!= (BOX obj1, BOX obj2)
    {
        return !(obj1.length == obj2.length 
                    && obj1.breadth == obj2.breadth 
                    && obj1.height == obj2.height);
    }

    // this is third one 'Equals'
    public override bool Equals(BOX obj)
    {
        return (length == obj.length 
                    && breadth == obj.breadth 
                    && height == obj.height);
    }
}

我想，我已经正确地编写了覆盖==!=Equals个运算符的代码.不过，我得到的编译错误如下.

'myNameSpace.BOX.Equals(myNameSpace.BOX)' is marked as an override 
but no suitable method found to override.

所以，问题是——如何覆盖上述运营商&amp；摆脱这个错误？