private void button2_Click(object sender, EventArgs e)

 {

     var ListA = new List<student>();

     ListA.Add(new student() { name = "张三", subject = "英语", score =  });

     ListA.Add(new student() { name = "李四", subject = "英语", score =  });

     ListA.Add(new student() { name = "王五", subject = "英语", score =  });

     ListA.Add(new student() { name = "李倩", subject = "英语", score =  });

     var ListB = new List<student>();

     ListB.Add(new student() { name = "李四", subject = "英语", score =  });

     ListB.Add(new student() { name = "王五", subject = "数学", score =  });

     ListB.Add(new student() { name = "赵六", subject = "数学", score =  });

     //使用Exists同样可以实现 字面上应该更好理解，而且效率要高些

     //从ListB中查找ListA中不包含的数据,根据name判断

     var exp2 = ListB.Where(a => !ListA.Exists(t => a.name.Contains(t.name))).ToList() as  List<student>;

     ListA.AddRange(exp2);

 }

 public class student

 {

     /// <summary>

     /// 姓名

     /// </summary>

     public string name;

     /// <summary>

     /// 科目

     /// </summary>

     public string subject;

     /// <summary>

     /// 分数

     /// </summary>

     public int score;

 }