Private Sub Command1_Click()
Dim str1 As String
Dim str2 As String
Dim arr1() As String
Dim arr2() As String
Dim i As Integer
Dim startLen As Integer'保留下一个单词的开始位置

RichTextBox2.SelStart = 0
RichTextBox2.SelLength = 0
arr1 = Split(RichTextBox1.Text, " ")
arr2 = Split(RichTextBox2.Text, " ")

For i = 0 To UBound(arr2)
    If StrComp(arr1(i), arr2(i), vbBinaryCompare) <> 0 Then
        RichTextBox2.SelStart = InStr(1, RichTextBox2.Text, arr2(i), vbTextCompare) - 1
        RichTextBox2.SelLength = Len(arr2(i))
        RichTextBox2.SelColor = vbRed
    ElseIf StrComp(arr1(i), arr2(i), vbBinaryCompare) = 0 Then
        RichTextBox2.SelStart = startLen
        RichTextBox2.SelLength = Len(arr2(i))
        RichTextBox2.SelColor = vbBlack
    End If
    startLen = startLen + Len(arr2(i)) + 1
Next i

End Sub