用VB制作一个加法器

Private Sub Command1_Click()
a = Val(Text1.Text)
b = Val(Text2.Text)
s = a + b
Text3 = s
End Sub
Private Sub Command2_Click()
Text1.Text = ""
Text2.Text = ""
Text3.Text = ""
Text1.SetFocus
End Sub
Private Sub Form_Load()
Dim a As Integer
Dim b As Integer
Dim s As Integer
End Sub
Private Sub Text1_KeyPress(KeyAscii As Integer)
If KeyAscii = 13 Then
KeyAscii = 0
Text2.SetFocus
End If
End Sub
Private Sub Text2_KeyPress(KeyAscii As Integer)
If KeyAscii = 13 Then
Call Command1_Click
KeyAscii = 0
Text3.SetFocus
End If
End Sub
Private Sub Text3_Change()
With Text3

.SelStart = Len(.Text)
.SetFocus
End With
End Sub
Private Sub Text3_KeyPress(KeyAscii As Integer)
If KeyAscii = 13 Then
Call Command2_Click
KeyAscii = 0
End If
E