Private Sub Command1_Click()

Dim a as Integer

a=Val(Text1.text) ‘将文本框中的数字文本转换成数值

a=2*a+1

Text1.text = StrA.

End Sub

程序运行时在文本框Text1中输入1，连续两次单击命令按钮Command1后，Text1中显示的内容是：（   ）

图1

图2

Dim c As String, i As Integer

Dim s As String, s1 As String

s = "Jishu_Xuankao_2020"

s1 =""

For i = 1 To Len(s) Step 2

  c = Mid(s, i, l)

  If c >= "a" And c <= "z" Then s1=c+s1

Next i

Text1. Text = s1

执行该程序段后，文本框Text1显示的内容是（  ）

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    ‘数组元素的总数

Dim a(1 To n) As Integer

Private Sub Form_Load()

‘该过程对数组a进行赋值,并在列表框List1中显示，代码略

End Sub

Private Sub Command1_Click()

Dim i As Integer, j As Integer,flag(1 To n) As Boolean

‘flag(i)记录第i个元素是否重复出现

For i = 1 To n      ‘flag(i)=true开始假设都只出现1次

 flag(i) = True

Next i

For i = 1 To n

 If flag(i) Then

  For j = i + 1 To n

    If Then flag(i) = False: flag(j) = False    ‘①

  Next j

 End If

Next i

For i = 1 To n

  If Then List2.AddItem Str(a(i))    ‘②

Next i

End Sub

①{#blank#}1{#/blank#} ②{#blank#}2{#/blank#}