class Program
    {
        static void Main(string[] args)
        {
            string sourceFile = @"..\..\Documents\Myppt12.pptx";
            string targetFile = @"..\..\Documents\Myppt11.pptx";
            MoveParagraphToPresentation(sourceFile, targetFile);
        }
        // Moves a paragraph range in a TextBody shape in the source document
        // to another TextBody shape in the target document.
        public static void MoveParagraphToPresentation(string sourceFile, string targetFile)
        {
            // Open the source file as read/write.
            using (PresentationDocument sourceDoc = PresentationDocument.Open(sourceFile, true))
            {
                // Open the target file as read/write.
                using (PresentationDocument targetDoc = PresentationDocument.Open(targetFile, true))
                {
                    // Get the first slide in the source presentation.
                    SlidePart slide1 = GetFirstSlide(sourceDoc);

                    // Get the first TextBody shape in it.
                    TextBody textBody1 = slide1.Slide.Descendants().First();

                    // Get the first paragraph in the TextBody shape.
                    // Note: "Drawing" is the alias of namespace DocumentFormat.OpenXml.Drawing
                    Drawing.Paragraph p1 = textBody1.Elements().First();

                    // Get the first slide in the target presentation.
                    SlidePart slide2 = GetFirstSlide(targetDoc);

                    // Get the first TextBody shape in it.
                    TextBody textBody2 = slide2.Slide.Descendants().First();

                    // Clone the source paragraph and insert the cloned. paragraph into the target TextBody shape.
                    // Passing "true" creates a deep clone, which creates a copy of the 
                    // Paragraph object and everything directly or indirectly referenced by that object.
                    textBody2.Append(p1.CloneNode(true));

                    // Remove the source paragraph from the source file.
                    textBody1.RemoveChild(p1);

                    // Replace the removed paragraph with a placeholder.
                    textBody1.AppendChild(new Drawing.Paragraph());

                    // Save the slide in the source file.
                    slide1.Slide.Save();

                    // Save the slide in the target file.
                    slide2.Slide.Save();
                }
            }
        }

        // Get the slide part of the first slide in the presentation document.
        public static SlidePart GetFirstSlide(PresentationDocument presentationDocument)
        {
            // Get relationship ID of the first slide
            PresentationPart part = presentationDocument.PresentationPart;
            SlideId slideId = part.Presentation.SlideIdList.GetFirstChild();
            string relId = slideId.RelationshipId;

            // Get the slide part by the relationship ID.
            SlidePart slidePart = (SlidePart)part.GetPartById(relId);

            return slidePart;
        }
    }

class Program
    {
        static void Main(string[] args)
        {
            string sourceFile = @"..\..\Documents\Myppt12.pptx";
            string targetFile = @"..\..\Documents\Myppt11.pptx";
            MoveParagraphToPresentation(sourceFile, targetFile);
        }
        public static void MoveParagraphToPresentation(string sourceFile, string targetFile)
        {
            string Text = "";

            //Initialize an instances of Presentation class 
            Presentation sourcePres = new Presentation(sourceFile, FileFormat.Pptx2010);

            IShape shp = sourcePres.Slides[0].Shapes[0];
            if (shp.Placeholder != null)
            {
                //Get text from the shape
                Text = ((IAutoShape)shp).TextFrame.Text;
                ((IAutoShape)shp).TextFrame.Text = "";
            }
            Presentation destPres = new Presentation(targetFile, FileFormat.Pptx2010);
            //Access first shape in first slide
            IShape destshp = destPres.Slides[0].Shapes[0];
            if (destshp.Placeholder != null)
            {
                //Get text from placeholder
                ((IAutoShape)destshp).TextFrame.Text += Text;
            }
            destPres.SaveToFile(@"..\..\Documents\Myppt11.pptx", FileFormat.Pptx2010);
        }
    }