C# Base keyword usage

using System;
using ;
using ;
namespace ConsoleApplication1
{
class Class4
{
//Declare 2 constructors
public Class4()
{
("Class4");
}
int i;
public Class4(int a)
{
i=a;
("Class:{0}", i);
}
public void SS()
{
("BOSS");
}
}
class Test:Class4
{
//Calling the parent class (without parameter) constructor
public Test()
: base()
{
}
//Calling the constructor of the parent class (with parameters)
public Test(int a)
: base(a)
{
();
}
}
class TT
{
static void Main()
{
Test T = new Test();
Test T1 = new Test(10);
}
}
}