Train auxiliary verbs app (android)

I would like to share and ask for feedback on the app i made. You practice auxiliary verbs with it.
https://play.google.com/apps/testing/air.com.patrickjansen.net.TENSEDRILLER

obs: it's in beta, almost ready to be released publicly.
obs: It also has a teachers mode.

Anxious to get some feedback from both users and teachers.

T.i.a
Patrick