题目内容：
下列程序代码段中，在单击命令按钮调用SelMid函数时，其运行结果为（ ）。Private Function SelMid(aStr As String) As String
Dim temp As String
Dim sLen As Integer
'temp=…’
sLen= Len(aStr)
i=l
Do While i<=sLen／2
temp= temp+ Mid(aStr,i,l)+ Mid(aStr,sLen -i+1,1)
i=i+l
Loop
SelMid= temp
End Function
Private Sub Commandl_Click()
Dim Str As String ．
Str="abcdef': Print SelMid(Str)
End Sub A．abcdef
B．afbecd
C．fedeba
D．defabc
参考答案：
答案解析：