O tempo verbal Inglês Present Perfect refere-se a algo iniciado no passado e que continua ate hoje, tendo portanto um tempo indefinido. 
Veja só:

Em portugues dizemos:"Eu trabalho aqui ha 2 anos" 
querendo dizer que entrei na empresa faz 2 anos e ainda estou la.

Poderiamos dizer também:"Tenho trabalhado aqui por 2 anos" 
sendo esta a forma do Present Perfect que apesar de "não existir oficialmente" na gramática portuguesa é usado tranquilamente no dia a dia,certo?

Em inglês ha uma diferença entre o uso desses dois tempos verbais.Veja:

With a finished time ( yesterday / last week , etc ... ), we use the Past Simple
Com um tempo definido (ontem / semana passada,etc.) usamos o Simple Past 

                              yesterday

                              last week

We arrived              at 3 o’clock

                              in 1995

                              six months ago

DO NOT USE the Present Perfect with a finished time .
NÃO USE o Present Perfect com tempo definido, ou terninado.

 Examples :

·       I saw Paula yesterday

·       Where were you on Sunday afternoon ? ( not “where have you been “ )

·       We didn’t have a holiday last year ( not “ we haven’t had “)

·       What did you do last night ? - I stayed home .

·       William Shakespeare lived from 1564 to 1616 . He was a writer . He wrote many plays and poems.

             
Use the Past Simple to ask “ when “, “ what time ? “
Use Past Simple (Passado Simples) para perguntar:- "quando" - "a que horas"

   When did they arrive ?  ( not “when have they arrived ? “ ) 

Dica: Visite a pagina Tempos Verbais(todos) e procure pelo Present / Past Perfect

                             Compare these sentences - compare estas frases

PRESENT PERFECT                         PAST SIMPLE (tempo definido ou ação terminada no passado)

I have lost my key                                        I lost my key last night

Bill has gone home                                       Bill went home ten minutes ago

Have you seen Ann ?                                     Did you see Ann on Saturday ?

 Have you ever been to Spain ?                     Did you go to Spain last year ?

My friend  has written many books                He wrote 5 books

The letter hasn’t arrived yet               The letter didn’t arrive yesterday

We’ve lived in Glasgow for 6 years        We lived in Glasgow for six years but now we live in Tokyo

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