Private Sub Command1_Click( )

   Dim x As Integer，y As Integer

   x = 8

   y = 10^x

   Text1.Text = Str(y)

End Sub                                                 

运行程序时，单击Command1后弹出如上图所示的出错提示，引起该错误的原因是（   ）

Private Sub Command1_Click()

  Dim a As Integer, b As Integer

  a = 10                                        '①

  b = 20                                        '②

  Text1.Text = "a+b=" + Val(a + b)              '③

End Sub                                         '④

Dim a(0 To 9) As Integer, t as Long

t=Val(Text1.Text)

Do While t<>0

 a(t Mod 10) = 1

 t = t \ 10

Loop

For i = 0 To 9

 x = x + a(i)

Next i

Text1中输入10242048，则程序执行后x的值为（  ）