French language Q&A Forum

Is there any trick as such to consider them? I often find myself confused in the gender parts. Thanks

In this example, I am wondering why soudainement is not used (adding "ment" to the feminine version of an adjective).

I am looking at this sentence and soudain seems to be used as an adverb/is that why no "ment".  If so would you please provide me with an example where soudainement might be used?  Many thanks. 

On regardait les lucioles, et soudain toutes ont disparu.

It says here that 'my nose is small but their noses are big' is translated to 'Mon nez est petit, mais leurs nez sont gros' . Is there a certain reason why it is "gros" isntead of "grand" ? Or is it just an optional thing?