using System;using System.Collections.Generic;using System.Linq;namespace DeferredExecutionExp{  class Program  {    static void Main(string[] args)    {      List<Student> studentList = new List<Student>()      {        new Student(){Id =1, Name="ZhangSan", Age=20},        new Student(){Id =2, Name=null, Age=21},        new Student(){Id =3, Name="Lisi", Age=22}      };      var queryedStudentList = studentList.Where(it => it.Name.Trim() != "ZhangSan");//(1)      if (queryedStudentList.Count() > 0)//(2)      {        foreach (var student in queryedStudentList)//(3)        {          Console.WriteLine(student.Name);        }      }    }  }  public class Student  {    public int Id { get; set; }    public string Name { get; set; }    public int Age { get; set; }  }}