I noted that in German, Spanish and Italian the "you (informal plural)" form of verbs is hardly offered. I would like to see many more sentences where this form is used, because I have a hard time learning them. In French this is different because the formal you is the same as the informal you plural.
I guess the rational behind the lack of this form in the Spanish exercices might be that in Latin American Spanish 'ustedes' often is used both for a formal and an informal address. But concerning German and Italian, it would certainly make sense to include more examples of these forms.