1. Unpublish default "Main Menu", because default "Home" under "Main Menu" is set to "All language" and it cannot be changed.
2. Enable System => Plugin => "Language Code" & "Language Filter"
3. Enable "Language Switcher": Content => Site Modules => Publish "Language Switcher"
4. install and enable language pack
5. Create two menus, eg. one for English and the other for Chinese
6. Create two categories and assign to its according languages.
7. Create two articles and assign to its according languages and make them as the "default" for each language's "Main Menu".
8. Associate two languages' catetories and articles to each other.