为此，编写了一个 VB 程序，功能如下：运行程序，窗体加载时随机产生 10 个随机整数，并在列表框 List1 中依次显示排序前数据，单击“排序”按钮 Command1，在列表框 List2 中

显示经过上述排序算法后的数据，运行结果如图 b 所示。实现上述功能的 VB 代码如下，但加框处代码有错，请改正。

Const n = 10

Dim a(1 To n) As Integer        '生成 n 个随机数，存储在 a 数组，代码略

Private Sub Command1_Click()

Dim i As Integer, j As Integer, t As Integer

For i = 2 To n

t = a(i)  :   j = i - 1

Do  While  t < a(j)

 a(j + 1) = a(j) j = j – 1

If     Then Exit Do  ①

Loop

       ②

Next i

For i = 1 To n

 List2.AddItem Str(a(i))

Next i

End Sub

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For i = 1 To 2

For j = 5 To i + 1 Step -1

If a(j) > a(i) Then

t = a(j): a(j) = a(i): a(i) = t

End If

Next j

Next i

数组元素a(1)到a(5)的值依次为“33，24，,4,16,77”，经过该程序段“加工”后，数组元素a(1)到a(5)的值依次为（   ）

a(1) = "231": a(2) = "34": a(3) = "23": a(4) = "234": a(5) = "123"

For i = 1 To 4

     For j = 1 To 5 - i

         If a(j) > a(j + 1) Then t = a(j): a(j) = a(j + 1): a(j + 1) = t

     Next j Next i

执行该程序段后，数组元素 a(1)到 a(5)的数据依次为（  ）

实现上述功能的VB程序如下：

待排序数据已存储在数组a中(a(1)~a(n))

For i= 1 To n-2

k= i

For j=    ‘①

If a(j)>a(k) Then k =j

Next j

If k<>i Then t= a(i)： a(i)= a(k)： a(k)=t

Next i

For i= 1 To n\ 2

j=2*i-1

If a(j)< a(j+ 1) Then t= a()： a()=a(j+ 1)： a(j+1)=t

Next i

For i=  ‘②

t= a(i)：j-i

Do While t> a(j)

a(j+1)=a()：j=j

Loop

   ‘③

Next i

上述程序段中3处方框处的代码分别为（  ）

Const n = 10

    Dim d(1 To n) As Integer, pm(1 To n) As Integer

    Private Sub Form_Load()

    '代码略，本过程功能：产生10个随机整数存数组d中，并在列表框list1 中显示。

    End Sub

    Private Sub Command1_Click()

    Dim i As Integer, j As Integer, k As Integer, t As Integer

    i = 1

    Do While i <= n - 1

    k = i

    For j = i + 1 To n

    If  Then k = j     ‘①

    Next j

    If i <> k Then t = d(i): d(i) = d(k): d(k) = t

    i = i + 1

    Loop

    pm(1) = 1

    For i = 2 To n

    If  Then     ‘②

    pm(i) = i

    Else

    pm(i) = pm(i - 1)

    End If

    Next i

    For i = 1 To n

    List2.AddItem Str(i) +" " +Str(d(i)) + " " + "第" + Str(pm(i)) + "名"

    Next I 

    End Sub

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