使用c#中的XmlDocument读取XML文件

我试图读取XML文件，但没有收到只有空格、制表符或新行的节点内容。请告诉我哪里错了。

XML文件：

<?xml version="1.0" encoding="UTF-8"?>
<root>
    <paragraph>
        <sentence>
            <sequence>
                <word>aaa</word>
                <space> </space>
            </sequence>
            <sequence>
                <word>bbb</word>
                <space>    </space>
            </sequence>
            <sequence>
                <word>ccc</word>
                <space>?!</space>
            </sequence>
        </sentence>
    </paragraph>
</root>

代码：

XmlDocument doc = new XmlDocument();
doc.Load("D:/Licenta/files/struct.xml");
XmlNodeList sentences = doc.DocumentElement.SelectNodes("/root/paragraph");
foreach (XmlNode sentence in sentences) {
    Console.WriteLine(sentence.InnerText);
}
Console.ReadLine();

输出：aaabbbccc？！