"The door is closed."

Translation: Drzwi są zamknięte.

[dfwgator]

Why "są" and not "jest"?

[tadjanow]

'drzwi' does not have a singular form

[chce_polski]

That's pretty weird.

[BrettAZAyres]

I understand its because the word "drzwi" is a plural but are there any cases that you would have to refer to it in a singular way? Can you force the context of a sentence to say "this 1 door is the only door out of the building" or will it always be a rough equivilent to "this 1 doors are the only doors out of the building"?

[Jellei]

Well, it's always "drzwi" in plural, so putting English grammar aside, to a Polish person those two sentences are completely identical.

I think it's really rare to have the need to make it clear you mean more than one.

[Ten_Pies_I_Brew]

If you wanted to say "this one door is big" (with emphasis on just this one), would that be "te jedne drzwi są duże"?

[Jellei]

It's a pretty unusual thing to say, but looks correct to me.