present perfect vs preterit

[Paul Zadi LOHOUROU]

Dear teachers and language experts , I would like to know how to use these two different tenses. When some studies or homeworks, I meet difficulties to use them. Well to clear my ideas I know how to use the present perfect when there is since or for in a sentence. But sometimes when there is not for nor since in a sentence and your asked to correct it by using the preterit or the present perfect ; it seems to be like a sword turning upon my head.That's why dear teatchers as a non-native I rely on you to clear up this serious matter so that my mind will be deliver from what seems to be a nightmare for me.

Best regards!

[boothling]

Can you give an example of the problem?

[MikeNewYork]

Dear teachers and language experts , I would like to know how to use these two different tenses. When some studies or homeworks, I meet difficulties to use them. Well to clear my ideas I know how to use the present perfect when there is since or for in a sentence. But sometimes when there is not for nor since in a sentence and your asked to correct it by using the preterit or the present perfect ; it seems to be like a sword turning upon my head.That's why dear teatchers as a non-native I rely on you to clear up this serious matter so that my mind will be deliver from what seems to be a nightmare for me.

Best regards!

This is a very difficult area, and it is one about which native speakers often disagree. IMO opinion, there is a large area of overlap with these tenses, an area in which either tense is acceptable and grammatical. At either side of this area, there are situations that clearly require one tense or the other. I encourage you to use the Internet (Google "present perfect") and read the information on many different sites. Then, when you have specific questions, come back and ask us.

[Paul Zadi LOHOUROU]

Can you give an example of the problem?

Here is the example: 1- Choose between the two sentences the correct one:
a- Christophe Colombus discovered America
b- Christophe Colombus has discovered America

[boothling]

Christopher Columbus discovered America is the better sentence.

Why?

This is how my teacher explained it to me today:

Christopher Columbus is dead. Because he no longer exists, we can't use the present perfect to describe things that he did. Instead, we use the past simple.

(I'm sure this explanation doesn't cover everything, but it worked for me.)

If I read a sentence like this:

A scientist has found a new species of fish (present perfect)

I assume that the discovery happened quite recently; and that the scientist is still alive and working.

[MikeNewYork]

Christopher Columbus discovered America is the better sentence.

Why?

This is how my teacher explained it to me today:

Christopher Columbus is dead. Because he no longer exists, we can't use the present perfect to describe things that he did. Instead, we use the past simple.

(I'm sure this explanation doesn't cover everything, but it worked for me.)

If I read a sentence like this:

A scientist has found a new species of fish (present perfect)

I assume that the discovery happened quite recently; and that the scientist is still alive and working.

I agree with your explanations as far as they go. Even if America were discovered in 1989 and Christopher Columbus were still alive, the simple past would be the correct form. If the fish discovery occurred yesterday, the present perfect would be correct. Even if the event happened a week ago, that would be true. It is difficult, however, to precisely define what "recently" means. Would it apply to a day, a week, a month, a year, a decade?