Linq中的Distinct怎么用

        private void button1_Click(object sender, EventArgs e)
        {
            Person p1 = new Person { Name = "小二", Sex = "男", Age = 30 };
            Person p2 = new Person { Name = "小三", Sex = "女", Age = 25 };
            Person p3 = new Person { Name = "小五", Sex = "男", Age = 27 };
            Person p4 = new Person { Name = "小四", Sex = "男", Age = 25 };
            Person p5 = new Person { Name = "小二", Sex = "男", Age = 30 };

            List<Person> ps = new List<Person>();
            ps.Add(p1);
            ps.Add(p2);
            ps.Add(p3);
            ps.Add(p4);

            //寻找有多少种性别
            List<string> n = ps.Select(q => q.Sex).Distinct().ToList();

            //过滤重复
            List<Person> p = ps.Select(q => q).Distinct().ToList();
        }
    }

    public class Person
    {
        public string Name { get; set; }
        public string Sex { get; set; }
        public int Age { get; set; }
    }
}