下列程序的执行结果为（ ）。
Private Sub Command1_Click()
Dim FirStr As String
FirSt="abcdef"
Print Pat(FirStr)
End Sub
Private Function Pat(xStr As String)As String
Dim tempStr As String，strLen As Integer
tempStr=" "
strLen=Len(xStr)
i=1
Do While i<=Len(xStr)-3
tempStr=tempStr+Mid(xStr，i，1)+Mid(xStr，strLen -i+1，1)
i=i+1
Loop
Pat=tempStr
End Function