somebody, everybody, someone, everyone - they are singular. so right way to say it would be: 'someone came and opened the door' (if you know the gender you could say 'someone came and he or she opened the door') with everybody is the same.... but you could say in another context: everybody came and when they opened the door something happened...

Everybody Nobody Somebody Anybody: they all take a singular VERB. Example: Everybody: is/has/wants/thinks etc He/She/It: is/has/wants/thinks etc BUT this is not true if you use a PRONOUN Example: Everybody came to the party and THEY all had a good time Nobody came to the party. THEY all told me THEY had other plans. What if somebody who is not invited comes to the party? What will you tell THEM? Yes, anybody can come to the party. Tell THEM THEY're all welcome but THEY need to bring THEIR own alcohol :)) (kidding) :)

thx all for your answers they were helpful ^^ I was just asking if I can use the pronoun THEY for a singular like [anyone, someone, no one...etc] if the gender is unknown ^^ thx

Question: Can I use "they" for these? Answer: Yes you can. Sentence Examples: Everybody left the room because they thought the music was terrible. Someone came in and they didn't close the door. Everyone began to talk because they were bored waiting for the bus. They is gender neutral > You can use it for men or women / or for either if you don't know.

Yes. In fact, it is the correct pronoun to use!