XML输出顺序错误

我用C#编写了一个简单的WCF web服务，它从数据库中返回记录。

WCF使用以下方法：getQuestionnaireForID?id=(questionnaireID)。Web服务从数据库中返回所有正确的记录，但是它们的顺序似乎不正确。

这是我希望XML的顺序：

<QuestionnaireXML xmlns="http://schemas.datacontract.org/2004/07/QuestionnaireDescriptor" xmlns:i="http://www.w3.org/2001/XMLSchema-instance">
    <QuestionnaireName>Sample Questionnaire</QuestionnaireName>
        <Questions>
            <Question>
                <QuestionID>297</QuestionID>
                <QuestionName>What is your favorite type of tree?</QuestionName>
                <Answers>
                    <Answer>
                        <AnswerTitle>Beech</AnswerTitle>
                    </Answer>
                    <Answer>
                        <AnswerTitle>Oak</AnswerTitle>
                    </Answer>
                </Answers>
            </Question>
            <Question>
                <QuestionID>298</QuestionID>
                <QuestionName>Windows or Mac?</QuestionName>
                <Answers>
                    <Answer>
                        <AnswerTitle>Mac</AnswerTitle>
                    </Answer>
                    <Answer>
                        <AnswerTitle>Windows</AnswerTitle>
                    </Answer>
                </Answers>
            </Question>
        </Questions>
</QuestionnaireXML>

但它当前按以下顺序返回：

<QuestionnaireXML xmlns="http://schemas.datacontract.org/2004/07/QuestionnaireDescriptor" xmlns:i="http://www.w3.org/2001/XMLSchema-instance">
    <QuestionnaireName>Hello sir how do you do today?</QuestionnaireName>
    <Questions>
        <Question>
            <Answers>
                <Answer>
                    <AnswerTitle>Beech</AnswerTitle>
                </Answer>
                <Answer>
                    <AnswerTitle>Oak</AnswerTitle>
                </Answer>
            </Answers>
            <QuestionID>297</QuestionID>
            <QuestionName>What is your favorite type of tree?</QuestionName>
        </Question>
        <Question>
            <Answers>
                <Answer>
                    <AnswerTitle>Mac</AnswerTitle>
                </Answer>
                <Answer>
                    <AnswerTitle>Windows</AnswerTitle>
                </Answer>
            </Answers>
            <QuestionID>298</QuestionID>
            <QuestionName>Windows or Mac?</QuestionName>
        </Question>
    </Questions>
</QuestionnaireXML>

我不确定这是由于一个未格式化的XML文档，还是因为我的循环顺序错误。这是我的WCF xml描述符。

[DataContract]
    public class QuestionnaireXML
    {
        OsqarSQL getData;
        DataTable DT;
        private String _questionnaireName;
        private List<Question> _Question = new List<Question>();
        public QuestionnaireXML(int QuestionnaireID)
        {
            // Loop through datatable for questionIDs and load the questions
            getData = new OsqarSQL();
            _questionnaireName = getData.GetQuestionnaireName(QuestionnaireID);
            DT = getData.GetQuestionIDWCF(QuestionnaireID);
            for (int i = 0; i < DT.Rows.Count; i++)
            {
                _Question.Add(new Question(Int32.Parse(DT.Rows[i][0].ToString())));
            }
        }
        // Define DataMembers for XML output
        [DataMember]
        public String QuestionnaireName
        {
            get { return _questionnaireName; }
            set { _questionnaireName = value; }
        }
        [DataMember]
        public List<Question> Questions
        {
            get { return _Question; }
            set { _Question = value; }
        }
    }
    [DataContract]
    public class Question
    {
        private Int32 _questionId;
        private String _questionName;
        OsqarSQL getData;
        DataTable DT;
        DataTable AT;
        private List<Answer> _Answer = new List<Answer>();
        public Question(int QuestionID)
        {
            getData = new OsqarSQL();
            DT = getData.GetQuestionNameWCF(QuestionID);
            _questionId = (int)DT.Rows[0][0];
            _questionName = DT.Rows[0][1].ToString();
            AT = getData.GetAnswerTitle(QuestionID);
            for (int i = 0; i < AT.Rows.Count; i++)
            {
                _Answer.Add(new Answer(Int32.Parse(AT.Rows[i][0].ToString())));
            }
        }
        // Define DataMembers for XML output
        [DataMember]
        public Int32 QuestionID
        {
            get { return _questionId; }
            set { _questionId = value; }
        }
        [DataMember]
        public String QuestionName
        {
            get { return _questionName; }
            set { _questionName = value; }
        }
        [DataMember]
        public List<Answer> Answers
        {
            get { return _Answer; }
            set { _Answer = value; }
        }
    }
    [DataContract]
    public class Answer
    {
        private Int32 _answerId;
        private String _answerTitle;
        OsqarSQL getData;
        DataTable DT;
        // Constructor Logic
        public Answer(int AnswerID)
        {
            getData = new OsqarSQL();
            DT = getData.GetAnswerTitleWcf(AnswerID);
            _answerTitle = DT.Rows[0][1].ToString();   
        }
        // Define DataMembers for XML output
        [DataMember]
        public String AnswerTitle
        {
            get { return _answerTitle; }
            set { _answerTitle = value; }
        }
    }

我该如何解决这个问题？在尝试解析XML时，它会引起问题吗？