s1 = Text1.Text : s2 = Text2.Text
i = 1: j = 1: k = 1
Do While ⑴
If j > Len(s2) Or i <= Len(s1) And Mid(s1, i, 1) < Mid(s2, j, 1) Then
⑵
Else
⑶
End If
Loop
Text3.Text = s
上述程序段3个方框处的代码分别为( )