1. 用26个互不重复的ASCI字符作为密码本，根据英文字母在字母表中位置，替换为密码本该位置的字符。现编写将英文字母加密的VB程序，在文本框Text1中输入明文，单击“加密”按钮Command1，在文本框Text2、Text3中输出产生的密码本和密文。程序运行界面如下图所示。

实现上述功能的VB代码如下，但加框处代码有错，请改正。

Private Sub Command1_Click()

Dim i As Integer, mw As String, jm As String

mw= Text1.Text: Text2.Text = my(26)

For i =1 To Len(mw)

c= Mid(mw, i, 1)

If c>="A" And c<="Z" Or c>="a"

And c<="2"Then

       ‘①

jm =jm+ Mid(Text2.Text, t, 1)

Else

jm=jm +c

End If

Next i

Text3.Text =jm

End Sub

Function my(n As Integer)As String

Dim s As String, i As Integer, x As Integer

s ="ABCDEFGHIKLMNOPQRSTUVWXYZabc-defghijklmnopqrstuvwxyz0123456789"

i=1

Do While i <=n

t=63-i

x =Int(Rnd()*t+1)

       ‘②

s = Mid(s, 1, x－1)+ Mid(s, x+1, t－x)

i=i+1

Loop

End Function

① ②