如何在使用open xml时修改文件流中的内容？

using DocumentFormat.OpenXml;
using DocumentFormat.OpenXml.Packaging;
using DocumentFormat.OpenXml.Wordprocessing;

using (WordprocessingDocument doc = WordprocessingDocument.Open(stream, true))
{
    // 进行修改操作
}

MainDocumentPart mainPart = doc.MainDocumentPart;
Document document = mainPart.Document;
Body body = document.Body;
// 根据需要定位到具体的段落、表格、文本等内容

// 修改段落文本
Paragraph paragraph = body.Elements<Paragraph>().FirstOrDefault();
Run run = paragraph.Elements<Run>().FirstOrDefault();
Text text = run.Elements<Text>().FirstOrDefault();
text.Text = "修改后的文本";

// 修改表格内容
Table table = body.Elements<Table>().FirstOrDefault();
TableRow row = table.Elements<TableRow>().FirstOrDefault();
TableCell cell = row.Elements<TableCell>().FirstOrDefault();
Paragraph cellParagraph = cell.Elements<Paragraph>().FirstOrDefault();
Run cellRun = cellParagraph.Elements<Run>().FirstOrDefault();
Text cellText = cellRun.Elements<Text>().FirstOrDefault();
cellText.Text = "修改后的表格内容";

doc.Save();