Const KeyWordColor = vbBlue
Const NormalForecolor = vbBlack
Dim KeyWords() As String
Private Sub Form_Load()
ReDim KeyWords(2)
KeyWords(0) = "GO"
KeyWords(1) = "Exit"
KeyWords(2) = "Return"
End Sub
 
Private Sub RichTextBox1_KeyPress(KeyAscii As Integer)
Dim CurPos As Integer
Dim WordPos1 As Integer
Dim i As Integer
If KeyAscii = vbKeySpace Then
With RichTextBox1
If .Text = "" Then Exit Sub
CurPos = .SelStart
WordPos1 = InStrRev(.Text, " ", .SelStart)
.SelStart = WordPos1
For i = 0 To UBound(KeyWords)
If UCase(Mid$(.Text, WordPos1 + 1, CurPos - WordPos1 + 1)) = UCase(KeyWords(i)) _
  Then
    .SelLength = CurPos - WordPos1 + 1
    .SelColor = KeyWordColor
    Exit For
Else
    .SelLength = CurPos - WordPos1 + 1
    .SelColor = NormalForecolor
End If
Next
.SelStart = CurPos
End With
End If
End Sub