Private Sub Command1Click()

  Dim a(-1 To 8) As Integer

  Dim i As Integer

  For i = -1 To 8

    a(i) = i * i

  Next i

  List1.AddItem Str (a(i))

End Sub

运行程序，单击命令按钮Command1后，出现的错误提示为

实现上述功能的VB代码如下，但加框处代码有错，请改正。

Private Sub Command1_Click()

Dim a(1 To 999) As Integer

Dim n As Integer

Dim s As String

For i=1 To 999

 a(i)=0

Next i

n=Val(Text1.Text)

s =“”

Do While n<>1     ‘分解质因子过程并统计质因子出现次数

For i = 2 To n

 Do While n Mod i = 0

  s = s&“  ”&i

  a(i)= a(i)+1

       ‘①

 Loop

Next i

Loop

Label4.Caption =“质因子分解过程:” +s

For j = 2 To 999     ‘判断是不是漂亮数

 If Then      ‘②

  Label1.Caption = “不是漂亮数”

  Exit For

 Else

  Label1.Caption =“漂亮数”

  End If

Next j

For j = 2 To 999     ‘在列表框输出质因数及对应的乘方数

 If a(j)>0 Then

  List1.Additem Str(j)+“ ”+Str(a(j))

 End If

Next j

End Sub

①{#blank#}1{#/blank#} ②{#blank#}2{#/blank#}