有如下VB程序段：
Dim a(1 To 10) As Integer
s = "7218634594": n = Len(s)
t = 0
For i = 1 To n - 1
a(i) = Val(Mid(s, i, 2))
Next i
For i = 1 To n - 2 Step 2
k = i
For j = i + 2 To n - 1 Step 2
If a(j) < a(k) Then k = j
Next j
If k <> i Then
temp = a(i): a(i) = a(k): a(k) = temp: t = t + 1
End If
Next i
Text1.Text = Str(t)
该程序段运行后，文本框Text1中显示的内容是

A．1	B．2
C．3	D．4

ual Basic中窗体文件的扩展名为（    ）

A．exe

B．frm

C．vbp

D．vbw

某Visual Basic程序如下：
Private Sub Command1_Click()
Dim x As Integer, y As Integer ,a As Integer ,b As Integer
X="0"
y=0
For a="1" To 3
x=x+1
For  b="2" to 4
y=y+1
Next b
Next a
Text1.text=str(a)
Text2.text=str(b)
End Sub
单击Command1按钮后，Text1显示    ①   ，Text2显示    ②   。

有如下Visual Basic程序段：
x=2.1Ifx>6.0Then
Label1.Caption="Pass"
Else
Label1.Caption="Fail"
EndIf
该程序段运行后,Label1标签上显示为_____________

下列选项中，正确的赋值语句是

A．a+b=6

B．8=a

C．b=a+8

D．-b=8