How do I get a left outer join in LINQ.

[abhijit]

Here is my code.

namespace LINQMatching
{
    class Student
    {
        public int StudentId { get; set; }
        public string Name { get; set; }
        public DateTime DateOfBirth { get; set; }
    }
    
    class Exam
    {
        public int TestId { get; set; }
        public string Name { get; set; }
    }
 
    class ExamScore
    {
        public int StudentId { get; set; }
        public int TestId { get; set; }
        public DateTime TestDate { get; set; }
        public decimal ? Score { get; set; }
    }
 
    class StudentScore
    {
        public int StudentId { get; set; }
        public string StudentName { get; set; }
        public int TestId { get; set; }
        public string TestName { get; set; }
        public decimal? TestScore { get; set; }
        public DateTime TestDate { get; set; }
    }
 
    class LinqMatching
    {
       static List<Student> students = new List<Student>();
       static List<Exam> exams = new List<Exam>();
       static List<ExamScore> scores = new List<ExamScore>();
 
        static void PopulateLists()
        {
            students = new List<Student>
                {
                    new Student {StudentId = 101, Name = "Steyn Jacob", DateOfBirth = new DateTime(1987, 1, 1)},
                    new Student {StudentId = 102, Name = "Elisha Martin", DateOfBirth = new DateTime(1989, 1, 1)},
                    new Student {StudentId = 103, Name = "Chad Gomes", DateOfBirth = new DateTime(1989, 11, 21)},
                    new Student {StudentId = 104, Name = "Jim Martin", DateOfBirth = new DateTime(1989, 12, 1)}
                };
            exams = new List<Exam>
                {
                    new Exam {TestId = 10, Name = "English"},
                    new Exam {TestId = 11, Name = "Math"},
                    new Exam {TestId = 13, Name = "Science"},
                    new Exam {TestId = 14, Name = "Geography"},
                    new Exam {TestId = 16, Name = "French"},
                    new Exam {TestId = 15, Name = "History"}
                };
            scores = new List<ExamScore>
                {
                    new ExamScore {TestId = 10, Score = 9.11M, StudentId = 101, TestDate = new DateTime(2013, 1, 1)},
                    new ExamScore {TestId = 11, Score = 8.11M, StudentId = 101, TestDate = new DateTime(2013, 2, 1)},
                    new ExamScore {TestId = 13, Score = 8.11M, StudentId = 101, TestDate = new DateTime(2013, 3, 1)},
                    new ExamScore {TestId = 10, Score = 9.11M, StudentId = 102, TestDate = new DateTime(2013, 1, 1)},
                    new ExamScore {TestId = 10, Score = 9.11M, StudentId = 104, TestDate = new DateTime(2013, 1, 1)}
                };
        }
 
        static void Main(string[] args)
        {
            var queryOut = from s in students
                           join e in scores on s.StudentId equals e.StudentId
                           join t in exams on e.TestId equals t.TestId
                           select new StudentScore
                               {
                                   StudentName = s.Name,
                                   TestId = e.TestId,
                                   TestName = t.Name,
                                   TestDate = e.TestDate,
                                   StudentId = s.StudentId,
                                   TestScore = e.Score
                               };
            foreach (var s in queryOut)
            {
                Console.WriteLine("{0} {1} {2} {3} {4}",s.StudentId, s.StudentName, s.TestName, s.TestDate, s.TestScore);
            }
        }
    }
}
 
i wish to know the syntax for getting this join to work. The output I expect from the query is
StudentName - TestName - TestDate - TestScore
 
The list must contain all the students and all the tests. If a student hasn't taken a test, the testscore and testdate would be empty.
How can I form this query?