运行如下Visual Basic程序，单击命令按钮Command1，出现如图所示的出错信息。发生“类型不匹配”错误时所执行的语句是（ ）

Private Sub Command1_Click()
Dim a As String, b As String, c As Integer
a = "Good"    '①
b = "bye"     '②
c =__________1__________'③
Text1.Text =" a" + b + c '④
End Sub

A．①

B．②

C．③

D．④

下面的程序代码是通过函数求出二个整数型变量a、b中的较大值，其中所定义的函数名是（   ）
Function max(a, b As Integer) As Integer
If a > b Then max = a  Else  max = b
End Function
Private Sub Command1_Click()
Dim a As Integer, b As Integer, s as integer
a =" Val(Text1.Text):" b = Val(Text2.Text)
s =" max(a," b)
Text3.Text = s
End Sub

A．Command1_Click

B．function

C．max

D．max(a, b As Integer)

在 Visual Basic 程序中要用到存储范围为-150000～150000 的某一整数变量，则该变量的类型应该定义为

A．Integer

B．Long

C．Single

D．Boolean

TEXT1.TEXT=C和C=" TEXT1.TEXT" 都没有语法错误；（   ）

下列声明语句中错误的是_________。

A．Const   var1=123	B．Dim  var2=’abc’
C．dim   a,b as string	D．dim  var3   as integer