public string FirstName { get; private set; }
 public string LastName { get; private set; }

 public string FirstName { get; }
 public string LastName { get; }

 public Student(string firstName, string lastName)
 {
 FirstName = firstName;
 LastName = lastName;
 }

 public string FirstName { get; set; } = "Corleone";
 public string LastName { get; set; } = "Mike";

 public Student Create() => new Student();

 public Student Create()
 {
  return new Student();
 }

 public string FullName => string.Format("{0},{1}", FirstName, LastName);

public string FullName
 {
  get
  {
   return string.Format("{0},{1}", FirstName, LastName);
  }
 }

 using static System.String;  // 先导入对应成员类型
 public bool IsNull(string str) => IsNullOrEmpty(str); 

 public bool IsNull(string str) => string.IsNullOrEmpty(str);

 var student = new Student();
 var firstName = student?.FirstName;

var student = new Student();

 string firstName = null;
 if (student != null)
 {
  firstName = student.FirstName;
 }

 int? age = student?.Age;

 var fullName = $"{student.FirstName},{student.LastName}";

 var fullName = string.Format("{0},{1}", student.FirstName, student.LastName);

 Console.WriteLine($"平均成绩：{student.GPA:F2}");

 Console.WriteLine($"平均成绩：{(student.GPA > 80 ? student.GPA : 0):F2}");

 var score = $"我的各科成绩：{ $"数学：{student.MathScores}；英语：{student.EnglishScore};"}";

try
 {
  throw new WebException("Request timed out..", WebExceptionStatus.Timeout);
 }
 catch (WebException webEx) when (webEx.Status == WebExceptionStatus.Timeout)
 {
  // Exception handling
 }

public string FullName(Student student)
 {
  if (student == null)
   throw new ArgumentNullException(nameof(student));

  return $"{student.FirstName},{student.LastName}";
 }

public static async Task<string> MakeRequestAndLogFailures()
 {
  await logMethodEntrance();
  try
  {
   // ....
   var responseText = await streamTask;
   return responseText;
  }
  catch (System.Net.Http.HttpRequestException e) when (e.Message.Contains("301"))
  {
   await logError("Recovered from redirect", e);
   return "Site Moved";
  }
  finally
  {
   await logMethodExit();
  }
 }

var list = new List<string>()
 {
  "Mike",
  "Jim"
 };
 
 var dic = new Dictionary<int, string>()
 {
  { 20, "Mike" },
  { 30, "Jim" }
 };

 var dic = new Dictionary<int, string>()
 {
  [20] = "Mike",
  [30] = "Jim"
 };

static Task DoThings()
 {
  return Task.FromResult(0);
 }
 
 Task.Run(DoThings); // 此处省略方法代码...