8/21/2019 ER Licao 29 http://slidepdf.com/reader/full/er-licao-29 1/3
8/21/2019 ER Licao 29
http://slidepdf.com/reader/full/er-licao-29 1/3
8/21/2019 ER Licao 29
http://slidepdf.com/reader/full/er-licao-29 2/3
8/21/2019 ER Licao 29
http://slidepdf.com/reader/full/er-licao-29 3/3