Translating English Present Perfect with 'since'

Question

you have been my best friend since we were children =  eres mi mejor amiga desde que éramos pequeñas.BUT In the previous exercise 'My Love Story´Since then, we've been joined at the hip   =  Desde entonces, hemos sido como uña y carneWhen I queried why in the second example it was incorrect to say somos como uña y carne,  Sylvia explained:
This construction with "hemos sido" (present perfect)
conveys the idea that the close relationship has been ongoing since
that point in the past. Your attempt was almost correct, but using
the present perfect aligns better with the context of an enduring
connection over time.I don't understand then why it is incorrect to say has estado mi mejor amiga desde que éramos pequeñasIs it correct to say " he vivido en esta casa desde hace 20 años" ? There is an enduring connection. The lessons with desde always state the use of the present.Gracias

Accepted Answer

Hola David

As already explained, the use of the present tense is the preferred one with that construction with 'since'.
However, I have also accepted as a valid answer the present perfect, since the difference in meaning between "has sido mi mejor amiga desde que éramos pequeñas" and "eres mi mejor amiga desde que éramos pequeñas" lies in the verb tense and temporal perspective:
Has sido mi mejor amiga desde que éramos pequeñas.
Uses the compound tense "has sido", which belongs to the past. Implies that the friendship has been present since the past and has continued over time until the present. It may suggest continuity in the friendship from childhood to now.
Eres mi mejor amiga desde que éramos pequeñas.
Uses the simple tense "eres", which belongs to the present. Suggests that the person is currently your best friend and has held that position from childhood to the present. Emphasizes the friendship in the current moment. Both expressions highlight the duration of the friendship since childhood, but one focuses more on continuity to the present (has sido), while the other emphasizes the current status of being the best friend (eres).

I hope this helps.
 
Un saludo
 
Silvia

Answer

You would say "has sido mi mejor amiga" because we use "ser" for relationships.

Answer

Marcos, I'm not querying the use of ser.

My problem is the inconsistency in which tense to use after 'desde' to express 'since'. In English it's always present perfect.

I don't understand why it's corrrect to say 'desde entonces hemos sido como uña y carne' but

incorrect to say 'has sido me mejor amiga desde que éramos pequeñas'

Answer

It's just that you wrote "has estado mi mejor amiga desde que éramos pequeñas", with "estado" instead of "sido". I thought that that might have been the error that the system triggered.

As to your question about not using the present, that's a good question. I look forward to Inma's answer.

Answer

You're correct Marcos. In the writing exercise I wrote 'has estado' and it was corrected to 'eres'

I'd still like to know if 'has sido mi mejor amiga' is possible. I find translating from the English Present Perfect very difficult with 'desde'