Roman languages, especially Spanish and to a lesser extent Portuguese have an endless amount of verbal phrases. Verbal phrases are constructions of two verbs, wherin the first verb loses completely its basic meaning and expresses intensity, progression, repetition, decision etc.. The other verb, that is in infinitive, is modified this way. (What is understood in English grammar books by verbal phrases doesn't correspond to what is understoodd by a verbal phrase in roman languages.) A verbal phrase in Portuguese contains in general the meaning of an adverb / adverbial and a verbal phrase is normally translated in English with an adverb / adverbial.
Most of the verbal phrases follows the construction verb (whose meaning is modified) + gerund. In most cases the verbs whose meaning is modified are andar, ir, continuar, vir. The following example illustrate the principle.
ir + gerundio
As
luzes
iam
-se acendendo
à medida
que
ela
passava.
The
light
went
themselves lightning
at the measure
that
she
passed.
The lights she passed by went on.
andar + gerundio
Ele
anda
estudando
este
assunto
há
algum
tempo.
He
goes
studying
this
issue
it has
some
time.
This is an issue she has been studying for years.
continuar + gerundio
Você
não
pode
continuar
fazendo
isso.
You
not
can
continue
doing
this.
You cannot continue like that.
vir + gerundio
Venho
dizendo
isso
há
anos.
I come
saying
this
it has
years.
That's what I have been saying for years.
If we put "venho trabalhando nisso" in google, don't forget the quotation marks, otherwise you well get all the pages that contains theses words in any order, we will see that very often there in an indication of time and that in the case of "estou trabalhando nisso" in general we don't have an indication of time, because the construction refers to the present of the speaker and no further indication is needed. The construction "Venho trabalhando nisso" has the same meaning as the pretérito perfeito composto "Tenho trabalhado nisso", see chapter 11.2. Both forms describe actions that started in the past and are repeated or last until the present of the speaker.
vir + gerundio
Eu
venho
trabalhando
nisso
por
quase
um
ano.
I
come
working
in this
since
almost
one
year.
I have been working on that for almost one year.
Venho
trabalhando
nisso
faz
quase
três
anos
e
ainda
não
tenho
certeza
se
estou
pronto.
Come
working
in this
makes
almost
three
years
and
still
not
I have
security
whether
I am
finished.
I have been working on that for one year and still I am not sure that I have finished.
Venho
trabalhando
nisso
há
quatro
anos.
Come
working
in this
it has
four
years.
I am working on this for four years now.
In most cases the construction ir + gerundio or andar + gerundio can be substituted by estar + gerundio. The difference is at most that estar + gerundio doesn't contain any kind of evaluation. It describes an ongoing action and nothing more. The construction andar + gerundio can have some secondary meanings that can however be different depending on the context.
andar + gerundio
O que você anda dizendo sobre a empresa é mesmo verdade?
Is the rumor you are spreading about the company is true?
O que você esta dizendo sobre a empresa é mesmo verdade?
Is it true what you are telling about the company?
The construction andar + gerundio can be interpreted. If someone tells something about someone again and again and with a certain intensity we can assume that he is emotionally involved and that he is not neutral. The construction estar + gerundio only describes on ongoing action at a precise moment. He doesn't do that repeatedly.
The same is true for the next example. If someone complains about something again and again to complain can become to moan for other people. Andar + gerundio is more intensive than estar + gerundio.
andar + gerundio with subjective evaluation
Andam se queixando porque as coisas vão mal.
They don't stop moaning that the things don't work.
Estão se queixando porque as coisas vão mal.
They are complaining that the things don't work.
How the construction andar + gerundio and ir + gerundio is to be translated depends on the context. However it is obvious that it makes a difference whether someone does something again and again until the present and beyond the present or if he does that only one time. If someone does the same thing again and again he must have a reason to do that.
The verbal phrase continuar + gerundio is easy. Continuar, to continue, keeps it original meaning.
continuar + gerundio
Mulheres continuam fazendo a maior parte do trabalho doméstico.
