No. All hubs must be written in English. You may incorporate foreign phrases in your hub to enhance the style, but you should always include the translation. Also, if it pertains to the topic about which your are writing, it would be permissible to include a foreign word or phrase. Again, for the sake of intelligibility, include the translation. For any questions regarding this policy, consult Hubpages rules and regulations. Vous comprenez? Do you understand? Of course if you wrote an instructional hub about the French language, it would be an aberration if you didn't have a lesson or two written in French with a parallel phrases or paragraphs translated into English with a grammatical explanation. I hope that gives you some insight. I speak some French, and would love to see you write a hub regarding some aspect of the language. It's such a beautiful and effluent tongue.