SIngular and pleural pronouns

The following was written to me recently by a friend in Germany: "SInd das Kängurus im Hintergrund?" Should this not be Sind sie Kängurus as we are discussing a pleural noun?

Hey John, "Sind das Kängurus im Hintergrund?" Means "are these kangaroos in the background". "Die" is not only the singular female article but also the article for all plural nouns. If it would be "Sind die Kängurus im Hintergrund?" that would mean "are the kangaroos in the background". "Sie" is formal form of you. "Sind sie Kängurus" means "Are you kangaroos" Lieben Gruß Paul

Thanks Paul. I learned German at school a long time ago and am vainly trying to pick it up again. Please excuse my ignorance. I'm still a little confused. I know that "Sie" with a capital S means formal "you" but I thought that "sie" with a small "s" can mean either they or she but not you. You being either Sie or du. Hence - Sind sie Kängurus? Are they kangaroos? It seems to me that "das" = that and the statement "Sind das Kängurus" would mean, are that kangaroos? Seemingly incorrect grammatically. I'm grateful for your help with this complex yet strangely enjoyable language. Regards John

Paul I'd very much appreciate a reply on the above. John

Hey John, Sorry for the late reply. I can understand your confusion. In this case "Sind das Kängurus" is, "are these kangaroos?" and can also mean "are they kangaroos?". "Sind das Kängurus" is a grammatically correct sentence although you wouldn't say in English "are that kangaroos?". "Sind sie Kängurus?" is not "Are they kangaroos?" but "Are you kangaroos?". "Sie" is the formal plural form. "Sind die Kängurus...?" is "Are the kangeroos...?" and it is an incomplete sentence. The grammar rule that you have to write the formal you always starting with a capital letter changed. You are allowed to write it in small letters if you prefer. When I adress a group of people I am used to ad "alle" so there is no misunderstanding. I would say:"Sind sie alle Kängurus?" Ich hoffe das hilft! Paul