某数据加密方法描述如下：先将字符转化为二进制的数据并显示在文本框Text2中，数据位数显示在标签Label1中。以16个数据为一段，将k个待加密数据依次分割成若干个数据段，剩余数据(个数小于16)为独立数据段。数据加密规则：数据个数等于16的数据段，在段内进行位置变换，得到加密数据段。数据个数小于16的数据段，直接得到加密数据段。依次合并加密数据段，即为最后的加密数据。位置变换的规
则如下：

具体界面如图所示：

请回答下列问题：
（1）已知k=34,则数组元素b(26)对应的值是数组a的_______________｡
（2）为实现上述功能,请在划线处填入合适的代码｡
Private Sub Command1_Click()
Dim a (1 To 1000) As Integer, b (1 To 1000)
As Integer
Dim n As Integer, m As Integer
Dim s As String, s1 As String, c As Integer,
ch As String
s = Text1.Text: Text2.Text = ""
n = Len(s)
k = 1
For i = 1 To n  '获取字符的二进制数据存放在数组a 中
n = Asc(Mid(s, i, 1))
Do While n <> 0
a(k) = n Mod 2
n = n \2
Text2.Text = Text2.Text + Str(a(k))
k = k + 1
Loop
Next i
__________
List1.Clear
'对字符二进制按规则进行位变换，变换后的数据存放
在数组 b 中并输出
For m = 1 To (k - 1) \16
For i = 1 To 4
b(16 ∗ (m - 1) + 4 ∗ (i - 1) + 1) = a((m- 1) ∗ 16 + i)
___________
Next i
For i = 1 To 3
b(16 ∗ (m - 1) + 4 ∗ (i - 1) + 3) = a((m- 1) ∗ 16 + 10 + i)
b(16 ∗ (m - 1) + 4 ∗ (i - 1) + 2) = a((m- 1) ∗ 16 + 17 - i)
Next i
For i = 1 To 2
b(16 ∗ (m - 1) + 13 + i) = a((m - 1) ∗16 + 4 + i)
Next i
For i = 1 To 4
s1 = ""
For j = 1 To 4
s1 = s1 + Str(b(16 ∗ (m - 1) + (i -1) ∗ 4 + j))
Next j
List1.AddItem s1
Next i
List1.AddItem ""
Next m
s1 = ""
For i = ((k - 1) \16) ∗ 16 + 1 To k - 1
b(i) = a(i)
If _______________ then
s1= s1 + Str(a(i))
List1.AddItem s1
s1 = ""
Else
s1 = s1 + Str(a(i))
End If
Next i
List1.AddItem s1
Text3.Text = ""
For i = 1 To k- 1
Text3.Text = Text3.Text + Str(b(i))
Next i
End Sub