In 7.6 Why is "Is that your suitcase? (polite) Ist das Ihr Koffer? the suitcase not in accusative case?

Is that your suitcase? (polite) Ist das Ihr Koffer?

Google translate confirms your answer is correct but this confuses since Der Koffer is masculine the answer implies Der Koffer is in the nominative case in this sentence while to me it seems like it is in the accusative.  Is it not the recipient of the question?

So I keep thinking it should be Is das Ihren Koffer?

I don't think so.  It is still the nominative case.  For example, it is grammatically correct to say "It is I" although the common usage is to say "it's me".  "is" suggests equivalence and not action and hence is nominative.

Thanks Byron.  Does this sometimes happen in sentences with "to be?"

Like "Das ist der Hund."  Or would it be "Das is den Hund?"

Ubrigens:

Durch die Art und Weise beendete ich nur die Premium- Level 1 Rocket- Deutschkurs . Ich dachte, es wäre eine schnelle Überprüfung , da ich drei Jahre Deutsche in der High School hatte und haben viel über die letzten sechs Monate studiert , aber ich fand die Praxis wirklich nützlich und landete auf sie einen ganzen Monat verbringen . Ich genieße wirklich den " Satz Tauch " nähern sich der Rakete Deutsch Leute verwenden . Sie können sich nicht vorstellen , wie viele vocubulary Listen und grammer Regeln, die ich auswendig gelernt habe, aber das half mir nicht wirklich die Sprache sprechen . Ich hoffe, dass Sie Spaß haben zu müssen. Ich sehe, Sie haben es schon seit mindestens drei Jahren und scheinen eine sehr fortgeschrittene Schüler zu sein . Danke fürs Helfen.

Yes, I think so.  The verb forms (am, is, are) imply existence or equivalency and not action, i.e. the noun or pronoun at the other end of the verb is not receiving action.  Hence, it would be correct to say, "I am he"  (awkward as it sounds.  the more common expression would be that's me technically incorrect but so widely used that no one would call you on it anymore.)  It would  be correct to say "I hit him" not "I hit he" because hit is an action verb and the receiving pronoun must be objective.

BTW, I'll take this opportunity to air one of my pet peeves.  People, particularly those who consider themselves well educated very often say "between you and I" which is wrong because between is a preposition and the following pronoun must take the objective form.

Regarding my German studies, I hit it pretty  hard and regularly for awhile, but haven't done much lately and so I'm losing it.  I must get back on it.

regards,

Byron