THE use of the Present Perfect tense

The Present Perfect denotes an action preceding the present moment but connected with it. It is used to denote:

1. Actions or states, which took place in the past and are connected with the present:

I have read the article (and can discuss it with you).

They have arrived (now we can go and see them).

It is frequently used with the adverbs already, before, ever, never, often, recently, still, yet, just, of late, etc.:

It has already started raining. (Take an umbrella). They have never been to London. They still haven't found an answer (There is no answer).

Note: In questions the adverb ‘already’ is used to express surprise that something has happened so soon:

Have you met them already?

2. Actions or states when their results are obvious in the present:

I 've broken the cup — look!

She has written the review — here it is.

3. Actions which take place in periods of time that are not over:

She has met a lot of people this week.

We have completed our research this year.

4. Actions completed before a definite moment in the future in adverbial clauses of time after the conjunctions when, as soon as, till, until, before, after.

I am leaving as soon as I' ve got the answer.

He won't talk to you until you have apologized.

5.Actions which started in the past, continued up to the moment of speaking, and are still going on. The preposition for is used to denote the whole period of duration; the preposition since is used to denote the starting point of the action.

She has lived here for three years.

She has lived here since last October.

This use of the Present Perfect is called the Present Perfect Inclusive. The form is translated into Russian by the Present or the Past imperfective. It is used:

(a) with the verbs which don't usually form continuous:

She has known about you for a week or so.

Она знает о тебе уже около недели.

(b) in negative sentences:

I haven't seen her since last week.

Я не вижу (не видела) ее с прошлой недели.

(с) with non-terminative verbs (to live, to study, to work, etc.):

I' ve worked at this problem for several months.

Я работаю над этой проблемой уже несколько месяцев.

Note 1: The Present Simple and not the Present Perfect is used in sentences of the following kind:

How long is it since you came here? – It is 2 hours since I came here.

Note 2: Mind the use of tenses in the following sentence:

It is the second time you have been late.