I have a doubt related to the construction of a simple use case, basicly i have 2 actors in my example, and i connected the first actor to some use cases in which 1 of them has some optional requirments.For example when a user ask a question he has the option to choose a theme but he don't need to do it (just a example forget the practice about this), my problem is related to my second actor, because i want him to be able to ask questions to and want somehow do a include to reuse that use case.But i don't want to let him have the optional chosing theme, i don't want him to choose a theme, how can i approach this? i don't see an example related to this, do i need to create a new use case for that? can't i reuse the old to do this?Thanks 
Use case extend for 1 actor
design;uml;use case