下列程序的执行结果为 Private Sub Command1_Click() Dim s1 As String, s2 As String s1= 'abcd' Call Transfer(s1, s2) Print s2 End Sub Private Sub Transfer (ByVal xstr As String, ystr As String) Dim tempstr As String i=Len(xstr) Do While i >=1 tempstr=tempstr + Mid(xstr, i, 1) i=i - 1 Loop ystr=te mpstr End Sub( )。