SIMPLE PAST or PAST PARTICIPLE?
I'm in doubt if these verbs are in SIMPLE PAST or PAST PARTICIPLE:

Eu tinha trabalhado - I had (worked)
Eu deveria ter trabalhado - I should have (worked)
Eu poderia ter trabalhado - I could have (worked)
Eu devo ter trabalhado - I must have (worked)

Anybody can help me ?

Question

SIMPLE PAST or PAST PARTICIPLE?
I'm in doubt if these verbs are in SIMPLE PAST or PAST PARTICIPLE:

Eu tinha trabalhado - I had (worked)
Eu deveria ter trabalhado - I should have (worked)
Eu poderia ter trabalhado - I could have (worked)
Eu devo ter trabalhado - I must have (worked)

Anybody can help me ?

Answer

Eu tinha trabalhado - I had (worked) Past Perfect

Eu deveria ter trabalhado - I should have (worked) Present Perfect

Eu poderia ter trabalhado - I could have (worked) Present Perfect

Eu devo ter trabalhado - I must have (worked) Present Perfect

Answer

Vou tentar te passar algumas noções:

Eu tenho visto(I have seen).
Ela tem ligado(She has called)

Obs: Você usa o Past Participle na frase quando algo aconteceu no passado e ainda acontece. Esse tópico é chamado de 'Present Perfect'.

Ex:I have lived here for about 3 years.(Eu moro aqui há mais ou menos 3 anos)
Ex:She has worked hard.(Ela tem trabalhado intensamente)

Obs:é comum usarmos o Past Participle para dizermos que "já" fizemos algo:

Ex:I´ve seen you before.(Já te vi antes)
EX:He´s lost to me.(Ele já perdeu pra mim).

Como nenhuma dessas frases representam ações que continuam acontecendo no presente, creio que sejam frases no simple past acompanhadas de modal verbs (should, could, must)