单项选择题

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