Требуются пояснения по коду

using System; 
using System.Collections.Generic; 
using System.Timers; 
using System.IO; 
 
namespace ConsoleApp15 
{ 
enum Education 
{ 
IBM, IU, SM, RK, RL, SGN 
} 
public class Person : IComparable 
 
{ 
protected string Name; 
protected string Family; 
protected byte Age; 
 
public Person() 
{ 
Name = ""; 
Family = ""; 
Age = 1; 
} 
public Person(string _f, string _n, byte _a) 
{ 
Family = _f; 
Name = _n; 
Age = _a; 
} 
public string StudentFamily 
{ 
get 
{ 
return Family; 
} 
set 
{ 
if (value != "") { Family = value; }; 
} 
} 
public string StudentName 
{ 
get 
{ 
return Name; 
} 
set 
{ 
if (value != "") { Name = value; }; 
} 
} 
public byte StudentAge 
{ 
get 
{ 
return Age; 
} 
set 
{ 
if (value != 1) { Age = value; }; 
} 
} 
public int CompareTo(object obj) 
 
{ 
Person p = (Person)obj; 
if (this.GetHashCode() < p.GetHashCode()) return -1; 
else if (this.GetHashCode() == p.GetHashCode()) return 0; 
else return 1; 
} 
 
public override bool Equals(object obj) 
{ 
if (obj == null) 
 
{ 
return false; 
} 
else 
{ 
Person local = (Person)obj; 
if (this.Family.Equals(local.Family) && 
this.Name.Equals(local.Name) && 
this.Age.Equals(local.Age)) 
{ return true; } 
else 
{ return false; } 
} 
 
} 
public override int GetHashCode() 
{ 
return this.Family.Length + this.Name.Length + Age; 
} 
 
class Test 
{ 
public DateTime DateTest; 
public byte TypeTest; 
public string NameTest; 
public byte MarkTest; 
public Test() 
{ 
this.DateTest = new DateTime(1990, 01, 01); 
this.TypeTest = 0; 
this.NameTest = ""; 
this.MarkTest = 0; 
} 
public Test(DateTime d, byte t, string n, byte m) 
{ 
this.DateTest = d; 
this.TypeTest = t; 
this.NameTest = n; 
this.MarkTest = m; 
} 
} 
class Student : Person, IComparable 
{ 
protected System.Collections.Generic.List<Test> Exams; 
//protected string Test; 
public Education Inst; 
public string NameG; 
 
public Student() : base() 
{ 
//this.Test = ""; 
this.Exams = new List<Test>(); 
this.NameG = ""; 
System.Random i = new Random(); 
 
 
} 
public Student(string d, string e, byte b, string n, int i) : base(d, e, b) 
{ 
this.NameG = n; 
System.Random p = new Random(); 
p.Next(); 
 
this.Exams = new List<Test>(); 
 
Exams.Add(new Test(new DateTime(), 0, "Algebra", (byte)p.Next(0,100))); 
Exams.Add(new Test(new DateTime(), 0, "Informatics", (byte)p.Next(0,100))); 
Exams.Add(new Test(new DateTime(), 0, "BI", (byte)p.Next(0,100))); 
Exams.Add(new Test(new DateTime(), 1, "Math", (byte)p.Next(0,100))); 
Exams.Add(new Test(new DateTime(), 1, "PE", (byte)p.Next(0,100))); 
Exams.Add(new Test(new DateTime(), 1, "History", (byte)p.Next(0,100))); 
 
//Random pp = new Random(); 
Inst = (Education)i; 
 
} 
 
public List<Test> ExamsList 
{ 
get { return Exams; } 
set { Exams = value; } 
} 
 
 
 
public double AverageScore() 
{ 
double avg = 0; 
 
foreach (Test t in Exams) 
{ 
avg+=t.MarkTest; 
} 
 
return avg / Exams.Count; 
} 
 
} 
class StudentCollection 
{ 
protected System.Collections.Generic.List<Student> ListStudents; 
public StudentCollection() 
{ 
this.ListStudents = new List<Student>(); 
p = new Random(); 
 
} 
Random p; 
public void AddDefaults() 
{ 
this.ListStudents.Add(new Student("White", "Elison", 20, "First",p.Next(0,5))); 
this.ListStudents.Add(new Student("Black", "Tom", 19, "First", p.Next(0, 5))); 
this.ListStudents.Add(new Student("Mountain", "Jack", 18, "First", p.Next(0, 5))); 
this.ListStudents.Add(new Student("Fox", "Andrew", 20, "First", p.Next(0, 5))); 
this.ListStudents.Add(new Student("Little", "Nina", 21, "First", p.Next(0, 5))); 
this.ListStudents.Add(new Student("Fisher", "Olivia", 19, "First", p.Next(0, 5))); 
this.ListStudents.Add(new Student("Apple", "Madisson", 18, "First", p.Next(0, 5))); 
this.ListStudents.Add(new Student("Tiyson", "Rachel", 19, "First", p.Next(0, 5))); 
this.ListStudents.Add(new Student("Swan", "Adeline", 20, "First", p.Next(0, 5))); 
this.ListStudents.Add(new Student("Simson", "Fill",
 
 
 
19, "First", p.Next(0, 5))); 
 
} 
void AddStudents(params Student[] Stds) 
{ 
this.ListStudents.AddRange(Stds); 
} 
 
public double MaxAverageScore() 
{ 
double max = ListStudents[0].AverageScore(); 
foreach (Student t in ListStudents) 
{ 
if (max < t.AverageScore()) 
max = t.AverageScore(); 
 
} 
return max; 
} 
 
public override string ToString() 
{ 
string result = ""; 
 
foreach (Student s in ListStudents) 
{ 
string tests; 
string exams = ""; 
string passes = ""; 
foreach (Test t in s.ExamsList) 
 
{ 
if (t.TypeTest == 0) 
exams += t.NameTest + " " + t.MarkTest.ToString() + " "; 
 
else 
passes += exams += t.NameTest + " " + t.MarkTest.ToString() + " "; 
} 
tests = "Exams:" + exams + "\nTests:" + passes; 
result +="Name: " + s.Family +" "+ s.Name+ "\nAge: "+ s.Age.ToString() + "\nFaculty: " + Enum.GetName(typeof(Education),(int)s.Inst) + "\nGroup: " + s.NameG + "\n" + tests + "\n\n"; 
 
} 
 
return result; 
} 
public string ToShortString() 
{ 
return this.ListStudents.ToString(); 
 
} 
 
public List<Student> SortStudents() 
{ 
ListStudents.Sort(); 
return ListStudents; 
 
} 
 
public StudentCollection FacultyFilter(int i) 
{ 
StudentCollection lst = new StudentCollection(); 
foreach (Student s in ListStudents) 
{ 
if ((int)s.Inst == i) 
{ 
lst.ListStudents.Add(s); 
} 
} 
 
return lst; 
} 
 
 
 
 
} 
class TestCollections 
{ 
private System.Collections.Generic.List<Person> ListPerson=new List<Person>(); 
private System.Collections.Generic.List<string> ListString=new List<string>(); 
private System.Collections.Generic.Dictionary<Person, Student> DictionaryPS; 
private System.Collections.Generic.Dictionary<string, Student> DictionarySS; 
private Dictionary<int, Student> d; 
public TestCollections(int count) 
{ 
d = new Dictionary<int, Student>(); 
for (int i = 0; i < count; i++) 
{ 
d.Add(i, AddTC(i)); 
} 
} 
 
public void TestTime() 
{ 
for (int i = 0; i < 100; i++) 
{ 
ListPerson.Add(new Person("Surname"+i,"Name"+i,(byte)i)); 
ListString.Add("Surname" + i + " " + "Name"); 
} 
// Timer tm = new Timer(1); 
DateTime tm = DateTime.Now; 
ListPerson.Find(new Predicate<Person>((p)=>(p == new Person("Surname99", "Name99", 99)))); 
DateTime tm1 = DateTime.Now; 
Console.WriteLine("Time to find in ListPerson:" +(tm - tm1).ToString()); 
 
DateTime dt = DateTime.Now; 
ListString.Find(new Predicate<String>((p) => (p == "Surname99 Name99"))); 
DateTime dt2 = DateTime.Now; 
Console.WriteLine("Time to find in ListString:" + (dt - dt2).ToString()); 
 
} 
 
private Student add() 
{ 
throw new NotImplementedException(); 
} 
 
public static Student AddTC(int a) 
{ 
Student st = new Student(); 
return (st); 
} 
 
} 
 
 
class StdCFamily : Comparer<Student> 
{ 
public override int Compare(Student s1, Student s2) 
{ 
return String.Compare(s1.Family, s2.Family); 
} 
} 
class StdCAge : Comparer<Student> 
{ 
public override int Compare(Student s1, Student s2) 
{ 
if (s1.Age > s2.Age) 
return 1; 
else if (s1.Age < s2.Age) 
return -1; 
else 
return 0; 
} 
} 
 
class StdCMark : Comparer<Student> 
{ 
public override int Compare(Student s1, Student s2) 
{ 
if (s1.AverageScore() > s2.AverageScore()) 
return 1; 
else if (s1.AverageScore() < s2.AverageScore()) 
return -1; 
else 
return 0; 
 
} 
} 
 
class Program 
{ 
static void Main(string[] args) 
{ 
StudentCollection sc = new StudentCollection(); 
sc.AddDefaults(); 
Console.WriteLine(sc.ToString()); 
Console.WriteLine("\nMaximum Average Score:"); 
Console.WriteLine(sc.MaxAverageScore()); 
Console.WriteLine("\nStudents of the second faculty:"); 
Console.WriteLine(sc.FacultyFilter(4).ToString()); 
TestCollections tc = new TestCollections(100); 
tc.TestTime(); 
Console.ReadLine(); 
 
 
} 
} 
}