编写VB程序,实现如下功能: 单击“排序数组a”按钮Command1时，对已有数组a的数据进行升序排列，并显示在文本框Label1中；单击“显示数组b”按钮Command2时，将升序数组b的数据显示在文本框Label2中；再单击“合并a和b”按钮Command3时，对数组a和数组b升序合并到字符串中，将合并后的数据在文本框Label3中显示。(运行效果如图所示)。实现上述功能的VB代码如下, 请在划线处填入合适代码。

Dim a(1 To 6) As Integer
Dim b(1 To 6) As Integer
Private Sub Command1_Click() '对数组a中的数据进行排序
Dim i As Integer, j As Integer ，k as integer
a(1) =" 53" :a(2) =" 18:a(3)" =" 62:a(4)" =" 22:a(5)" =" 6:a(6)" = 25
s = ""
For i =" 1" To 5
k = i
For j =" i" + 1 To 6
If a(k) > a(j) Then ①
Next j
If i <> k Then
t =" a(k):" a(k) =" a(i):" a(i) = t
End If
Next i
For i =" 1" To 6
s =" s" + Str(a(i))
Next i
Label1.Caption = s
End Sub
Private Sub Command2_Click()
b(1) =" 3:" b(2) =" 8:" b(3) =" 15:" b(4) =" 27:" b(5) =" 38:" b(6) = 49
'此处部分代码省略
End Sub
Private Sub Command3_Click()
'将数组a和b中的数据逐个比较后添加到新的字符串s中，并将s在label3中显示
i =" 1:" j =" 1:" s = ""
Do While i <=" 6"     ②   j <= 6   '如果两数组都还有数据未合并
If   ③    Then
s =" s" + Str(a(i)) : i =" i" + 1
Else
s =" s" + Str(b(j)) : j =" j" + 1
End If
Loop
Do While i <= 6 '只有数组a还有数据未合并
s =" s" + Str(a(i)) : i =" i" + 1
Loop
Do While j <= 6 '只有数组b还有数据未合并
s =" s" + Str(b(j)) : j =" j" + 1
Loop
Label3.Caption = s
End Sub