I finished my work/I have finished my work.

I finished my work.
I have finished my work.

What is the difference of these sentences?

When 'have' is used does it change tense or just small difference in meaning?

Thanks in advance.

Re: have

"I finished" is the simple past.
"I have finished" is the present perfect.

Adding "have" does indeed change the tense. Have you studied the various forms of the past tense?

Re: have

Past tenses are simple past, past continous, past perfect.Is there any difference in meaning in above sentences?It seems that simple past and present perfect can be used interchangeably. Present perfect is always past and then why it is present tense?

It's called the "present perfect" because it includes the word "have" which is the present tense of the verb "have".

I finish. (Present tense)
I finished. (Simple past)
I have finished. (Present perfect)
I had finished. (Past perfect)
I am finishing. (Present continuous)
I was finishing. (Simple past continuous)
I have been finishing. (Present perfect continuous)
I had been finishing. (Past perfect continuous)

Note that in the continuous, there would be something after the relevant form of "finish".

Both the simple past and the present perfect are used to describe an event which happened in the past and which is now over. We use the simple past usually with a time marker and the present perfect when the time period is unspecified or unimportant.

I lived in Madrid from February 2009 until August 2010.
I have lived in Madrid.

I ate an apple for breakfast.
I have eaten an apple.

I bought bread yesterday.
I have bought bread.

However, sometimes the present perfect is used with something which looks like a time marker. For example, "I have bought bread at the same shop for ten years". The present perfect is used there to indicate that you still buy bread at the same store you have bought it at for the last ten years. If you no longer buy bread there, you would say "I bought bread at the same store for ten years but then I realised that the artisan bakery round the corner sells much better bread so now I buy it there".

I read about present perfect from some other website. What I inferred is that we use present perfect when it is revelant at present.

I did my home work.
I have done my home work so I am free now.

In the first sentence, finishing home work has nothing to do with present. But in the second sentence, finishing homework is relevant at present so it is present perfect tense.

I could be wrong.

'The present perfect tense ... is used when an action that happened in the past continues to have a strong connection in the present.'── quoted from http://esl.fis.edu/grammar/rules/presperf.htm

I finished my work before I went to bed.── There is no connection in the present.
I have finished my work, so I am going to bed.── There is a connection in the present.

The connection to the present can be implicit in the situation, too. A child might look up from the dining room table and say "I've finished my homework!" The unspoken "...so I can play Pokémon Go now, right?" justifies the present perfect.

rock-onn said:

I finished my work.
I have finished my work.

What is the difference of these sentences?

When 'have' is used does it change tense or just small difference in meaning?

Thanks in advance.

Click to expand...

"I have finished my work," implies that the act of finishing your work just occurred.
"I finished my work," implies that the act of finishing your work happened before now.

http://www.englishpage.com/verbpage/presentperfect.html

I found this link to be very helpful.