JUST: a short time ago.
Would you like something to eat?
No thanks, I’ve just had lunch.
ALREADY: some time before now.
She has already booked a table. (She did it some time before now).
Don’t forget to post the letter, will you? I’ve already posted it.
YET: the speaker is expecting something to happen: to ask if something has happened or to say that something has happened.
Has it stopped raining yet?
I haven’t told them about the accident yet.
Has she arrived yet?
I’m hungry. Is dinner ready yet?
Have you finished your homework yet?
It’s ten o’clock and Tom hasn’t got up yet.
SINCE and FOR
We use since and for to say how long something has been happening.
Since: we use since when we say the beginning of a period of time.
For: we use for when we are talking about a period of time.
a long time
Present Perfect + for and since
Using the present perfect, we can define a period of time before now by considering its duration, with for + a period of time, or by considering its starting point, with since + a point in time.
For + a period of time
- for six years, for a week, for a month, for hours, for two hours.
- I have worked here for five years.
Since + a point in time
- since this morning, since last week, since yesterday,
- since I was a child, since Wednesday, since 2 o’clock.
- I have worked here since 1990.
present perfect with for
- She has lived here for twenty years.
- We have taught at this school for a long time.
- Alice has been married for three months.
- They have been at the hotel for a week.
present perfect with since
- She has lived here since 1980.
- We have taught at this school since 1965
- Alice has been married since March 2nd.
- They have been at the hotel since last Tuesday.
Present perfect + just, before, already and yet
PRESENT PERFECT + just and before
indicates that the action has happened in the very recent past and it is completed, e.g.
a. I’ve just lost my car keys and can’t leave for work.
b. Don’t call John, I’ve just done it.
Just can be placed before the main verb (past participle).
indicates the existence of past events, and emphasizing the pastness of the event with a redundant before e.g.
a. She has seen the movie before.
b. I have met her before the summer.
Before is usually placed at the end of the sentence.
PRESENT PERFECT + already and yet
a. I’ve already drunk three coffees this morning. (and you’re offering me another one!)
b. Don’t write to John, I’ve already done it.
It is also used in questions:
- Have you already written to John?
- Has she finished her homework already?
already can be placed before the main verb (past participle) or at the end of the sentence:
- I have already been to Tokyo.
- I have been to Tokyo already.
is used in negative statements and questions, to mean (not) in the period of time between before now and now, (not) up to and including the present. e.g.
- Have you met Judy yet?
- I haven’t visited the Tate Gallery yet.
- Has he arrived yet?
- They haven’t eaten yet.
Yet is usually placed at the end of the sentence.