using System;
class obj_Sample_Class
{
    public int i=10;
}
class MainClass
{
static void Main()
  {
    object a;
    a=100;
    Console.WriteLine(a);
    Console.WriteLine(a.GetType());
    Console.WriteLine(a.ToString());
    a=new obj_Sample_Class();
    obj_Sample_Class classRef;
    classRef=(obj_Sample_Class)a;
    Console.WriteLine(classRef.i);
  }
}

输出的结果为:
100
System.Int32
100
10

请问GetType()和ToString()是什么意思啊?
谢谢拉