实现上述功能的VB程序如下，但加框处代码有错，请改正。

Const n = 10

Dim a(1 To n) As Integer

Private Sub Command1_Click()

  Dim i As Integer, j As Integer, t As Integer, bottom As Integer

  '获取排序前数据依次存储在数组a 中，并在文本框Text1 中显示。代码略

  bottom = n : i = 1

  Do While i <= bottom - 1

    For j = bottom To i + 1 Step -1

        If  Then     ‘⑴

            t = a(j): a(j) = a(j - 1): a(j - 1) = t

        ElseIf a(j) = a(j - 1) Then ' 相邻两个数据相等，进行剔除处理

                 ‘⑵

            bottom = bottom - 1

        End If

    Next j

    i = i + 1

  Loop

Text2.Text = " "

For i = 1 To bottom

    Text2.Text = Text2.Text + Str(a(i))

Next i

End Sub

⑴{#blank#}1{#/blank#} ⑵{#blank#}2{#/blank#} 

count=0

For i=1 To 20

    a(i) =Int(Rnd*100) + 1

Next i

For i= 1 To 20

    ①

Next i

For i= 1 To 100

    If b(i) <> 0 Then count =count+1

Next i

Label 1.caption=“不重复数字个数”+Str(count)

为实现上述功能，则程序①处应填入的语句为（  ）

请回答下列问题：

①x=y    ②y=x    ③t=x    ④x=t    ⑤y=t    ⑥t=y