Perfect tense usage

Question

When is the Perfect tense used? All examples illustrating Perfect are always answer to the some question. So there is no way when i can simple said:

"I have written a note" or "I had written a note"

,right? I need to say that instead:

I wrote a note

But if someone asking me, like : "Did you finish a note?", then i need to use Perfect:

"Yes, i just have written a note" or "Yes, i had written a note yesterday"

Am i right?

Answer 1

In addition to what Guffa has written in his answer, the (present) perfect usually expresses a current state resulting from a past action - either an accomplishment, or something that has consequences. For example:

• She has arrived (so she is now here)
• I have come (and am still here)
• I have studied a lot (so I know many things)
• I have spent a lot of time in the gym (so I am fit)
• I have finished my homework (so I can watch television)
• I have bought a car (and so I now have one)
• I have eaten (so I don't want more food)

The past perfect (/pluperfect) does the same, but talking about a state in the past resulting from a prior action:

• I had studied a lot (so I knew many things).

Answer 2

In TEFL we usually teach four areas where Present Perfect is used:

• events in an unspecified past - this has been covered by Guffa
• events with some sort of relevance to the present - psmears has dealt with that one

if I could just add:

• events in a current unfinished time period, that's to say: today, this morning (depending on time of day), this week, this year etc.
• use with certain words, such as: ever, never, since, for (but for can also be used with Past Simple) eg:

I have lived in Warsaw for ten years / since 2000 (and am still here)

Before that I lived in London for eight years

Answer 3

No, you can use either form in either case, depending on what you want to express.

Use past tense when you mean a specific point in time in the past:

I wrote a note yesterday morning.

Even if the specific point in time isn't specified, the form still implies that there exists a known point in time where it occurred:

I wrote a note.

Use present perfect for an unknown or undisclosed point in time in the past:

I have written a note.

Each works either on their own or as an answer to a question.

If you want to express a specific point in time, you can't use present perfect:

I have written a note last monday. [Wrong]

You have to use past tense for that:

I wrote a note last monday.

Answer 4

Most linguists recognize only two English tenses, present and past. The verb form in the sentence I have written a note is made up of the present tense of the auxiliary verb have and the past participle of the main verb, write. It is used to express perfect aspect, which ‘most typically expresses a state resulting from an earlier event’ (R L Trask in ‘Language and Linguistics: The Key Concepts’. When the auxiliary verb is in the past tense the events are placed a stage further back in time.