mein vs meinen
Er ist mein Bruder.
Shouldn't it be meinen because it's accusative case and mein transforms into meinen? While Bruder ist der Bruder, masculine.
I got in some confusion with.
My advice is to find some videos on you tube of verbs that go with accusative or dativ (learn german with ania or learn german with jenny)! In German I found out that this is a rule which says some verbs go just with one case.
the verb SEIN goes with nominative, but the verb HABEN goes with accusative. For example:
Er IST mein Bruder. Ich HABE einen Bruder.
Das ist mein Ball. Ich habe einen Ball.
I hope this is helpful! I've learnt it this way, please someone correct me if I'm wrong!
p.s. Don't use only one app for learning new language because it's not enough! The disadvantage of duolingo is that you don't have the explanation WHY are the sentences like that, so you get confused!
I use two translators (available on-line for free) along with Duolingo. Often, the translators do not agree with the Duolingo translation due to simple things. For example: Wir haben kein Brot. Duolingo insists that the translation is "We have not got bread" while other translators (and me) translate to "We have no bread." So.. use multiple sources to get the best answer.