1"i will see you next wednesday" said Mary to her friend => 2His sister said,"i don't buy this book" =>

`1.` Mary told her friend that she would see him/her the following wednesday.

    `-` will`->` would 

    `-` next.... `->` the following....

`2.` His sister said that she didn't buy that book.

    `-` lùi thì `:` HTĐ `->` QKĐ

     `-` Đổi chủ ngữ `:` I `->` she

     `-` this `->` that