Are you just here? You are a little early, aren’t you?
Are you already here? You are a little early, aren’t you?
Are you yet here? I thought you had gone.
Are you still here? I thought you had gone.
I haven’t yet decided what to do.
I haven’t decided what to do yet.
They haven’t still come - I am worried about them.
They still haven’t come - I am worried about them.
They are here yet.
They are here already.
Is it midnight already? Time for bed then.
Is it midnight yet? I can’t wait to open the champagne to celebrate the new year.
Have you finished already? It didn’t take you very long.
Have you finished yet? You seem to be taking a long time.
They have already arrived. Typical, they always arrive early.
They have just arrived. Go help them with their suitcases.
They haven’t arrived yet. But I imagine they will be here soon in any case.
They still haven’t arrived. Where are they? I hope they haven’t had an accident.
already + the affirmative: an event has taken place which may or may not be surprising (I have already seen this film so I don’t want to see it again - neutral; ten students have come already, I was only expecting six).
already + the interrogative: the questioner expresses some surprise (I saw their car in the outside. Are they already here?) or great surprise (Heavens! Are they back already? I thought they were going to be at least two hours). Note that the position of already in the phrase indicates the level of surprise.
yet + the interrogative: the questioner wants to know if an event has taken place or not, there is no urgency or surprise involved (Are they here yet?). By making the question negative the questioner adds a sense of surprise (Aren’t they here yet?)
yet + the negative: a simple statement that something has not happened within the expected time frame (They haven’t finished yet.)
still: the speaker is surprised in the interrogative (Are they still here? I thought
they would be gone by now) and either neutral or surprised in the affirmative (They are still here. When are they going to go?)
just + affirmative only: refers to an event that happened very recently (They have just left - only a couple of minutes ago in fact)
Note: Consult a good grammar to learn about the correct position for all these words (already, just, still, yet) and what tenses to use as these differ between US and GB English. For the sake of space and simplicity, the exercises below just test the meaning of the words.