C#环境中设置上标和下标

在涉及到单位时，我们经常需要使用到上标和下标，在网上搜了一下，RICHTEXTBOX还是挺好用的，用法如下：
private void form_Load(object sender, EventArgs e)
        {           
            Font richFont = new Font("宋体", 10);
            richTextBox1.Font=richFont; //在c#中需要定义一FONT变量，在VB中可以不定义，直接设置FONT属性
            richTextBox1.Text =  "H2SO4";
            OffsetRichText(richTextBox1,1,1,2);
            OffsetRichText(richTextBox1, 4, 1, -2);
        }

private void OffsetRichText(RichTextBox box, int iStart, int iLength, int iOffset)
        {

            box.SelectionStart = iStart;
            box.SelectionLength = iLength;
            Font richFont1 = new Font("宋体", box.Font.Size - System.Math.Abs(iOffset));
            box.SelectionFont = richFont1;
            box.SelectionCharOffset =iOffset;
            box.SelectionStart = 0;
            box.SelectionLength = 0;

        }