我是XML的新手。但是有人被要求将第三方工具quizmaker合并到我们的应用程序中，其中应用程序的结果如下所示。
<?xml version="1.0" encoding="UTF-8"?>
<quizReport xmlns="http://www.ispringsolutions.com/ispring/quizbuilder/quizresults" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.ispringsolutions.com/ispring/quizbuilder/quizresults quizReport.xsd" version="1">
<quizSettings quizType="graded" maxScore="80" maxNormalizedScore="100" timeLimit="0">
<passingPercent>0.75</passingPercent>
</quizSettings>
<summary score="30" percent="0.375" time="69">
<variables />
</summary>
<questions>
<multipleChoiceQuestion id="{EB2FBA26-B728-45B1-A360-5C66CBF217A6}" status="incorrect" maxPoints="10" maxAttempts="1" awardedPoints="0" usedAttempts="1">
<direction>When meeting the executive do you</direction>
<answers correctAnswerIndex="2" userAnswerIndex="3">
<answer>Give him a firm handshake</answer>
<answer>Give him a firm handshake and a bow</answer>
<answer>Give him a soft handshake and a bow</answer>
<answer>Bow only</answer>
</answers>
</multipleChoiceQuestion>
<multipleChoiceQuestion id="{BB9874C0-FC02-4A26-B7DA-72471D8EC55E}" status="incorrect" maxPoints="10" maxAttempts="1" awardedPoints="0" usedAttempts="1">
<direction>He hands you his business card do you</direction>
<answers correctAnswerIndex="2" userAnswerIndex="1">
<answer>Take the card with your left hand and immediately put it in your pocket</answer>
<answer>Take the card with your right hand and put it on the table</answer>
<answer>Take the card with both hands and study it intently</answer>
</answers>
</multipleChoiceQuestion>
<multipleChoiceQuestion id="{4CDAA21F-34A9-4C0A-946E-87BCFCDE6A80}" status="correct" maxPoints="10" maxAttempts="1" awardedPoints="10" usedAttempts="1">
<direction>During your initial conversation the Company Y executive says something very important that you want to remember. Is it acceptable to write the information on his business card?</direction>
<answers correctAnswerIndex="1" userAnswerIndex="1">
<answer>Yes</answer>
<answer>No</answer>
</answers>
</multipleChoiceQuestion>
<multipleChoiceQuestion id="{5ACF826A-755B-4608-96B3-962678AD2036}" status="incorrect" maxPoints="10" maxAttempts="1" awardedPoints="0" usedAttempts="1">
<direction>The Company Y executive hands you a contract that he wants you to sign before your discussions begin do you</direction>
<answers correctAnswerIndex="2" userAnswerIndex="0">
<answer>Tell him that the contract will come at the end after they have reached a mutual decision</answer>
<answer>Sign the contract, it can always be changed later</answer>
<answer>Tell him that you will need to have it reviewed by your manager for approval</answer>
</answers>
</multipleChoiceQuestion>
<multipleChoiceQuestion id="{6C2EBA2E-9D54-4435-9C93-2A6FC7B18C7B}" status="incorrect" maxPoints="10" maxAttempts="1" awardedPoints="0" usedAttempts="1">
<direction>During the meeting you discover you did not turn off your cell phone and it rings. It is from another customer who is also very important, do you</direction>
<answers correctAnswerIndex="1" userAnswerIndex="0">
<answer>Say "excuse me one moment" and answer the call</answer>
<answer>Let the call go to voice mail and turn off your ringer</answer>
</answers>
</multipleChoiceQuestion>
<multipleChoiceQuestion id="{A4496C25-BD0A-42FB-8250-8BC398908FCC}" status="correct" maxPoints="10" maxAttempts="1" awardedPoints="10" usedAttempts="1">
<direction>After the first day of discussions the company Y executive invites you for a drink do you</direction>
<answers correctAnswerIndex="0" userAnswerIndex="0">
<answer>Politely accept</answer>
<answer>Politely decline</answer>
</answers>
</multipleChoiceQuestion>
<multipleChoiceQuestion id="{112B78AB-9051-48DC-B2F7-80564F04A21D}" status="correct" maxPoints="10" maxAttempts="1" awardedPoints="10" usedAttempts="1">
<direction>The next morning you realize that you have a conference call scheduled with another customer that could potentially make you 10 minutes late for your meeting with the Company Y executive do you</direction>
<answers correctAnswerIndex="1" userAnswerIndex="1">
<answer>Keep the conference call and explain the circumstances to the Company Y executive</answer>
<answer>Reschedule the conference call so that you are on time for the meeting with company Y</answer>
</answers>
</multipleChoiceQuestion>
<multipleChoiceQuestion id="{E9ACCE66-828A-416F-AF1F-BE6672F09F81}" status="incorrect" maxPoints="10" maxAttempts="1" awardedPoints="0" usedAttempts="1">
<direction>You have reached a final agreement and it is time to sign which choice is UNACCEPTABLE?</direction>
<answers correctAnswerIndex="1" userAnswerIndex="0">
<answer>Giving the Company Y executive a gift in appreciation</answer>
<answer>Signing the contract with your favorite red pen</answer>
<answer>Giving the executive a soft pat on the back</answer>
</answers>
</multipleChoiceQuestion>
</questions>
</quizReport>
我想要完成的是非常简单的，即将此XML中的Questions节点下的所有问题存储到我们的数据库中
Dim myXML As String = dt(0)("dr")
Dim doc As New XmlDocument
doc.LoadXml(myXML)
Dim nodes As XmlNode
nodes = doc.SelectSingleNode("/quizReport/questions")
Dim dc As New Dictionary(Of String, String)
Dim j As Integer = 0
For Each snode As XmlNode In nodes.ChildNodes
dc.Add(snode.Attributes("id").Value, snode.SelectSingleNode("direction").InnerText)
j += 1
Next
但我始终将节点变量视为 NOTHING ，或者选择单个节点不返回任何内容。很想知道我做错了什么