参考答案

'正确的程序
Private Sub Command1_Click()
    Dim a As Long, a1 As Long, a2 As Long
    Dim k As Integer, n As Integer
    For k = 0 To 2
        If Op1(k).Value Then
            n = Val(Op1(k).Caption)
        End If
    Next k
    a1 = 1
    a2 = 1
    For k = 3 To n
        a = a1 + a2
        a1 = a2
        a2 = a
    Next k
    Text1.Text = a
End Sub