下列程序的执行结果为Private Sub Command1_Click() Dim FirStr As String FirSt= abcdef Print Pat(FirStr)End SubPrivate Function Pat(xStr As String)As String Dim tempStr As String，strLen As Integer tempStr= strLen=Len(xStr) i=1 Do While i tempStr=tempStr+Mid(xStr，i，1)+Mid(xStr，strLen -i+1，1) i=i+1 Loop Pat=tempStrEnd Function
A．abcdef
B．afbecd
C．fedcba
D．defabc