"Otworzyliśmy drzwi."

Translation: We opened the door.

[Zimowski]

DL suggests two correct solutions:

We'd opened a door.
We opened the door.

I wrote "We opened a door". Is something wrong with this answer? Why can we open "the door" but not "a door" here?

[immery]

It has to be a missing translation, from Polish side there is no way of saying if this is "a door" the door", "doors" or "the doors", although plural without clarification is less likely.

also otworzyliśmy can be "have opened", "had opened", or "opened"

But maybe there is an English rule.

[Yola448704]

drzwi (plural noun) - door/ doors

Otworzyliśmy drzwi - We have opened a/the door/ (the) doors

[tgbarnett]

Why can't it be "We opened the doors"? What if it's a double door? (what's the Polish for "We opened the doors?")

[PabloPiskunow]

It should be correct. Actually, in Polish "drzwi" is a plural noun with no singular version. So all doors are doors in Polish.

[Jellei]

Sure, it works.