I can't believe what I am seeing!

Am I understanding you correctly?

2. an action going on at the present period of time.

• Are you writing a new book?

No cakes for me. I'm slimming.

She's spending a good deal on dresses of late.

3. actions generally characterising the person denoted by the subject, bringing out the person's typical traits. Such sentences are emotionally coloured, expressing irritation, disapproval, praise, etc. In such sentences the adverbials always or constantly are obligatory.

• You're always showing off!

She's constantly complaining that she has so much to do.

4. actions which will take place in the near future due to one's previous decision. The action is regarded as something definitely settled (mostly verbs of motion such as to move, to come, to go, to leave, to return, to start are used).

• He's returning on Monday. The boat is sailing next week.

Note: The Present Progressive of the verb to go + infinitive is commonly used to denote future fulfillment of the present situation:

• I'm going to study Italian. It is going to snow.

She's going to have a baby.

5. an action in progress which is simultaneous with some other action or state denoted by the verb in the Simple Present. It is used in adverbial clauses of time and condition after the conjunctions when, while, as long as, if, in case, unless.

• I never talk when I am working.

You must always watch the traffic lights when you're crossing the street. Try not to make much noise when you are stirring your tea.

The present perfect

The Present Perfect is an analytical form which is built up by means of the auxiliary verb to have in the Simple Present and Participle II of the notional verb.

• I have worked. He has worked. We have met at last.

The same auxiliary verb is used to form the interrogative and the negative forms.

• Have you worked? He has not worked.

The Present Perfect is used in present time contexts, i. e. conversations, newspaper and radio reports, lectures and letters. It is not found in narration where reference is usually made to past events. The Present Perfect may be resultative (exclusive) and durative (inclusive).

I. The Present Perfect Resultative (Exclusive) is used to denote a completed action connected with the present through its result.

• I've bought a good dictionary.

You can't see her, she has gone home.

The Present Perfect may be found with certain adverbs of indefinite time and frequency such as ever, just, already, before, never, not... yet, lately, of late, so far.

• Have you heard of him lately?

I haven't even had coffee yet.

We' haven't done much so far.

Notes:

a) The Present Perfect is possible with adverbial modifiers of time that denote a period of time which is not over yet, e.g. today, this morning, this week, this month, this year.

But if the period is over, the Simple Past is used.

• — Did you read the article in The Times this morning? (it is no longer morning)

— No, I haven't had time to look at the paper today, (today is not over yet)

b) In special questions introduced by where, how, who, what, why, what... for both the Present Perfect and the Past Simple are possible. The choice of tense in such cases is situational.

Compare:

• Why have you done this to me? (I'm upset)

Why did you do this? (at a certain past moment)

In when-questions only the Simple Past is used.

• When did you go there? When did it happen?

с) The Present Perfect is used in adverbial clauses of time introduced, by the conjunctions when, before, as soon as, till and until to stress the completion of the action of the subordinate clause before the action of the principal one.

• We'll see about it when you've had your tea.