Dim a(1 To 1 000)As String

  Dim b(1 To 2)As Integer

  N=Len(Text1．Text)

  For i=1 To n

    a(i)=Mid(Text1．Text，i，1)

  Next i

  DO While n>l

    If ASC(a(n))>=Asc(a(n-1))Then

       m=1

    Else

      m=2

    End If

    b(m)=b(m)+1

    n=n-1

  Loop

数组b各元素的初始值都为0，文本框Text1的内容为“2018Python”。执行程序后，变量b(1)的值为（  ）

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

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#} 

Dim a(1 To 15) As Integer

Private Sub Form_Load()

  Dim i As Integer, t As Integer

  Dim s1 As String, s2 As String

  Randomize

  s1 = ""

  For i = 1 To 15

    a(i) =  ①    

    s1 = s1 + Str(a(i))

  Next i

  Text1.Text = s1

End Sub

Private Sub Com1_Click()

  s2 = ""

  For i = 1 To 15

    s2 =  ②    

  Next i

  Text2.Text = s2

End Sub