单击命令按钮时，下列程序代码的执行结果为()。Private Function PickMid(xStrAs String)As Sting Dim tempStrAs String Dim strLenAs IntegerTempStr=" "StrLen=Len(xStr)i=1 Do While i＜=strLen/2　tempStr=tempStr+Mid(xStr,i,1)+Mid(xStr,strLen-i+1,1)　i=i+1LoopPickMid=tempStr End FunctionPrivate SubCommand1_Click() Dim FirstStrAs StringFirstStr="abcdef"Print PickMid(FirstStr) End Sub