Ir/vir/ver - the verbs of my nightmares
I tend to mix up these three verbs a lot. Since they were all introduced in my tree, I almost always have multiple attempts to get them right.
The conjugation of them goes as follows (I skipped tu and vós):
ir (to go)
vou vai vamos vão
vir (to come)
venho vem vimos vêm
ver (to see)
vejo vê vemos veem
To you know some technique to remember these? Is there a difference between pronunciation e.g. between "vem", "vêm" and "veem"?
About the pronunciation question: all the words sound the same in Brazilian Portuguese (Edit: that's an oversimplification, see other comments). The Portuguese pronounce "veem" as two distinct syllables. Listen here:
In general there is no easy way to remember the conjugations of irregular verbs. On the other hand it's not too hard to memorise the rules for conjugating regular verbs and there is a trick that should help you fully conjugate "ver".
If you conjugate "vir" as if it were a regular verb what you produce is the conjugation of "ver" for most tenses. The exceptions are: the future, the conditional and the personal infinitive which are found by following the regular rules for "ver"; and the present tenses which, being irregular, are the only ones that must be memorised.
An observation that may prove useful is that the present tense of "ver" is very similar to the present tense of "ler" (to read) and the present tense of "vir" is very similar to the present tense of "ter" (to have):
In which dialect do people pronounce veem like vem? Fairly sure that is nonstandard in Rio de Janeiro. Vê-em here. Two syllables, ê is closer to i than the nasalized em which is closer to é, and ê is not nasal at all while em is more nasal than an English speaker pronuncing eng.
In which dialect do people pronounce veem like vem?
Well, based purely on the very few forvo.com samples available I'd say the "Sulista" dialect. Listen to this woman from Paraná pronounce the word in the sentence "Vocês vêem tantos filmes, mas não entendem." ("veem" was still spelled "vêem" then).
It's easy to forget how many different accents there are in Brazil. The fact that there really isn't one that can be called definitive means saying something like "all the words sound the same", as I did, is bound to be only a half-truth (as evidenced by your comment and also by what vitor3cotta says elsewhere in this discussion). I didn't think it was too contentious, though, as some Brazilians agree: see this quote from an article on “vem”, “vêm” and “veem” taken from resumoescolar.com.br:
Quando utilizadas de forma oral, quase não há diferença entre as três. Sua pronúncia é a mesma, o que pode gerar confusão quando aplicadas de forma escrita. Como oralmente todas possuem a fonética da palavra “vêm”, ao empregar os três termos em diferentes orações é difícil escolher a forma correta.
Nonetheless, I'm sorry if I misled anyone.
She has a diphthong where I would have a hiatus, yes.
But then again, I don't pronounce vem as a monophthong, it is sort of like veng, with ng representing a nasalized velar approximant rather than a nasalized velar stop (think of the n in the word cansaço). In her case, I hear 'veing', which is intermediate between my vem and my veem.
Interesting, thanks. Unfortunately we can't hear how she says "vem" and "vêm" to compare. For what it's worth, Duolingo's TTS does distinguish between "vem"/"vêm" and "veem". I'll give my earlier comment a health warning. :)
as a native i can't say a memorization technique, but from the last question, there is a subtle difference in veem, like a double E, the other two are the same. A curiosity is for the verb to have (ter) in the singular (he she) tem, and in the plural (they ) eles têm (e nós temos) the pronunciation is the same