I was learning Korean on Duolingo and found that the following sentence is accepted.
Everyone jump!
I filled in Everyone jumps and got wrong. The comment section says it must be Everyone jump because in the imperative sentence the conjugation does not happen.
Is this correct? I have never learned it at my school. Does this only apply to pronouns like everybody and anytime or to any nouns?
"Everyone jump!" is an imperative sentence, which takes the bare form of the verb. "Everyone jumps!" is also technically grammatical but far less likely to be used in practice (as I would interpret it as being a statement of fact, that every person, at some point in their life, has jumped or will jump).
The verb form for imperative sentences is easier to see in this other example:
Be quiet!
It's important to note that imperative sentences don't have subjects. The word that looks like a subject (everyone in your sentence) is actually a vocative, which is basically a word used to get someone's attention so they know you're talking to them. (It's often recommended that it have a comma to offset it.) In fact it is possible to move the vocative to the end of the sentence with no change in meaning:
Jump, everyone!
Another reason we know that vocatives aren't the subject is because they can be used in sentences that already have subjects:
Everyone, you need to come with me.
Vocatives will usually be someone's name or their title (ma'am, dad, professor). You can also use the pronoun you (though that's perhaps a bit rude) or another second person pronoun (which you may come across in various dialects). It's also possible to use a phrase like "whoever took my sandwich".
The imperative and subjunctive conjugate in the same way, therefore there's no change in the verb form according to subject.
The only English verb that has a unique infinitive form from the rest of its forms is be, so this is the only time it tends to stands out.
90% of the time the subject of an imperative is you, and is understood and not explicitly expressed, so this isn't often thought about.
I request that he be aware of the situation.
Be aware of this situation.
I request that everyone be aware of the situation.
Everyone be aware of this situation.
The short answer is that when you command "Jump!", you are saying "You jump".
"Everyone jumps" is descriptive. "Everyone needs to jump" is persuasive. "Everyone, jump!" is a command.
