Where to find french dictionary for ispell?

I am editing documents in French with Emacs, ispell comes will English dictiona开发者_如何学Pythonry by default. When I try ispell-change-dictionary, it proposes francais-tex, francais7 and francais in the list. But after choosing anyone, and doing ispell-word, it tells me Error: The file "/usr/lib/aspell/francais" can not be opened for reading. Then I check the folder /usr/lib/aspell, indeed there is no "french" file in it.

So could anyone tell me where to find these french dictionaries and put them in the folder?

PS: I am using ubuntu...

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you need to install package like aspell-fr or something like. issue command apt-cache search aspell- to get list of all available dictionaries, or use graphical tools to find dictionary...