图1

请在下列程序代码的基础上按照要求设计该程序, 完善程序中的划线部分。

Dim n As Integer, a1 As Integer, a2 As Integer, a3 As Integer

Function f(x) As Boolean

f = True

      For i = 2 To Sqr(x)

         If x Mod i = 0 Then      ①     

Next i

End Function

Private Sub Command1_Click()

n =      ②       

For a1 = 2 To n

 For a2 = a1 To n

  For a3 = a2 To n

   If     ③      And f(a1) And f(a2) And f(a3) Then

    List1.AddItem (Str(a1) + " " + Str(a2) + " " + Str(a3))

   End If

  Next a3

 Next a2

Next a1

End Sub

其中①处填入{#blank#}1{#/blank#}；②处填入{#blank#}2{#/blank#}；③处填入{#blank#}3{#/blank#}

Private Sub Command1_Click()

i＝1

____①____

Do While____②____

____③____

j＝j－1 ′④

Loop

Text1.Text＝Str(i)

Text2.Text＝Str(j)

End Sub