German Verbs Trainer

All of the verb not exist in app why!!?

Won't allow me to register by email or link my account.

I would have given this app 5 stars except that there is a serious flaw: in the verb quiz, there is no way to tell if "sie" indicates "she" or "they." This destroys my perfect streak every time I use the quiz. It is very unfair and I don't believe that the developers couldn't fix this if they wanted to. I have noticed that other users have had a problem with this issue also. If you'd fix this one issue, I could give this app 5 stars. As long as this major fault persists, I will feel that I was generous in giving it three.