请问结果是什么，解释一下为什么？

[古市轩]

class People
{
String name;
int age;
People()
{
}
People(String name,int age)
{
this.name=name;
this.age=age;
System.out.println("in people");
}
}

class Student extends People
{
String school;
Student()
{
this(null,0,null);
System.out.println("in student1");
}
Student(String name,int age,String school)
{
super(name,age);
this.school=school;
System.out.println("in student2");
}
}


class Graduate extends Student
{
Graduate()
{
System.out.println("in graduate");
}
}

class Exam3_16
{
public static void main(String [] args)
{
People p=new Graduate();
}
}

//请解释一下结果！