Bonjour - does anyone know of a site where one can post sentences and have the grammar and structure checked?  As i practice writing I come up with sentences that I'm not sure are correct and i cannot always find the corresponding lesson for posting the question.  I'm wondering if anyone can provide some advice or is there a reliable tool that one can use for such a purpose?

Merci d'avance.

Bill, I'm not sure that you'll see this since your request is from a year ago but I'll answer just in case you do. The only site I know of for grammar and structure checking is :

BonPatron.com

It can be used for free with small amounts of text.

No. Je resterai ici jusqu'au temps que je doive partir (grammatically correct but not good). The pronoun "ce" replaces "le temps", so you don't use both. Also, only one "que" to introduce the subjunctive.