以下是您的代码，我仅被修改....

Following is your code , I am Modified only ....

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       im X As Integer = 0
      Dim i As Integer
      Dim TextBoxLength As Integer = 0

      TextBoxLength = TextBox1.Text.Length

      For i = 0 To TextBoxLength - 1
          X = X + 1
          If TextBox1.Text.Substring(i) = " " Then
              TextBox1.Text = TextBox1.Text.Replace(" ", (20 - X))
          End If

      Next i

请说明以下内容
1. TextBox1.Text.Replace("，(20-X))?和20-x?
2.您想做什么?

Please explain following things
1. TextBox1.Text.Replace(" ", (20 - X))? and 20 - x ?
2. What do you want to do exactly ?