“Door” in Polish is a strange word. Like “pants” in English, it’s always plural — drzwi. It’s likely because it’s etymologically connected to “tree” and “wood,” and since old doors were made of planks, it makes sense to call them something like “planks” (though that’s not what drzwi translates to literally).
This morning, the Boy went to tell K as she was getting ready for a shower that he’d heard a scratching at the door, that it was Bida, our cat, who was trying to get his attention so that he would let her in, that he heard it and wondered what it was, that he’d figured it out, and that he let her in. K stood patiently, towel wrapped around her, listening to this whole story patiently, then asked, in Polish, for privacy: “Could you please shut the door so that I could shower?”
He replied, in English: “I’ll close them and lock them so no one will come in.” He applied Polish grammar to English, pluralizing a word that would be plural in Polish but is singular in English.