如何修复winformc#中字符串生成器字符串的长度

在我的项目中，我使用StringBuilder在RichEditBox中创建一个表。但在我的专栏中，数据值彼此不同。所以它看起来像是经过洗牌的数据。但是我期望的输出是完全固定表中数据的长度。在我的输出中，我可以看到这个表已经正确地完成了。

谁能说如何在c#中固定StringBuilder字符串的长度?

Connection();
try
{
    string Today = "Student Test Mark Details";
    string Line = "----------------------------------";
    SqlCommand cmd = new SqlCommand();
    cmd.CommandType = CommandType.Text;
    cmd = new SqlCommand("select ExaminationName, ExaminationCenter, ExaminationDate, Subjects, MarkObtained, Total, Percentage, Grade from StudentMarksHistory where StudentCode='" + ICBEStudentCode.Text + "' and ExaminationName='" + TBExaminationName.Text + "' and ClassName='" + ICBEClassSection.Text + "' and Remark='Record Saved'", cs);
    StringBuilder paragraph = new StringBuilder();
    SqlDataReader dr = cmd.ExecuteReader();
                paragraph.Append(Today).Append("'t'n");
                paragraph.Append(Line).Append("'t'n'n'n'n'n");
                paragraph.Append("ExamName").Append("'t");
                paragraph.Append("ExamCenter").Append("'t");
                paragraph.Append("ExamDate").Append("'t");
                paragraph.Append("Subject").Append("'t't't");
                paragraph.Append("Mark").Append("'t");
                paragraph.Append("Total").Append("'t");
                paragraph.Append("Percentage").Append("'t");
                paragraph.Append("Grade").Append("'n'n");
                while (dr.Read())
                {
                    DateTime DateName = Convert.ToDateTime(dr["ExaminationDate"]);
                    string subject = dr["Subjects"].ToString().Trim();
                    //int Len = subject.Length;
                    //subject = subject.ToString().PadRight(50 - Len, ' ');
                    paragraph.Append(dr["ExaminationName"].ToString()).Append("'t");
                    paragraph.Append(dr["ExaminationCenter"].ToString()).Append("'t");
                    paragraph.Append(DateName.ToString("dd/MM/yyyy")).Append("'t");
                    paragraph.Append(subject);
                    paragraph.Append(' ', 15 - subject.Length);
                    //paragraph.Append(subject.PadRight(100));
                    paragraph.Append(dr["MarkObtained"].ToString()).Append("'t");
                    paragraph.Append(dr["Total"].ToString()).Append("'t");
                    paragraph.Append(dr["Percentage"].ToString()).Append("'t");
                    paragraph.Append(dr["Grade"].ToString()).Append("'n");
                }
                string Notes = "************[ Minimum Pass Mark is 35 ]*************";
                paragraph.Append(" ").Append("'n'n'n'n");
                paragraph.Append(Notes).Append("'r'n");
                dr.Close();
                cs.Close();
            }
            RTBMessage.Text = paragraph.ToString();
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
        }

结果expceted:

                                   Student Test Mark Details
                              ----------------------------------

ExamName        ExamCenter      ExamDate        Subject                 Mark    Total   
Class Test 1    Room No1        24/05/2013      STOREDPROCEDURE           97       404  
Class Test 1    Room No1        25/05/2013      DOTNET                   86       404     
Class Test 1    Room No1        26/05/2013      TAMIL                    80       404        
Class Test 1    Room No1        23/05/2013      SOCIAL                   80       404                                    
Class Test 1    Room No1        27/05/2013      COMPUTER                 61       404         

                          ************[ Minimum Pass Mark is 35 ]*************