difference between "о" and "об"

What's the difference between "о" and "об"?

You say: "ti zabotishsya obo vsem" "ti govorish o nem"

thanks.

(Sorry for not typing in Russian, my computer is not set up for it)

"O" is used before consonant, and "об" before vowel.
"Обо" you can meet in some collocations such as "обо всем", "обо мне", "обо всех" etc.

yeah, so why "obo vsem" and not "o vsem"?
Is there a rule?

I don't believe so. There are just a set of words that use обо rather than o.

It has to do with words that start with certain consonant clusters. Notice that all the following words start with two or more consonants. Similarly with к and с, перед. Real honest-to-goodness Russian speakers will give you a few more odd-ball items in this category.

And, just like our parallel situation with choosing "a" or "an", you will come across mixups. You have heard people say "an historic" while pronouncing the "h".

Personally, I always want to say во фразе, although I have no clue as to whether I should be saying в фразе, which would be /ffraz'i/.

Missed the second part of your question. There are a very, very few words before which о becomes обо. We have probably met them both in this thread. I can't think of any others. You have a similar thing with other vowel-less prepositions in phrases like ото всюду 'from all over'.

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Originally Posted by chaika

Personally, I always want to say во фразе,

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And that's correct.

I'd say в фразе. It seems to me that в/во фразе is hardly ever used in Russian. We normally say в этой фразе, в его фразе etc. What do you think?

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Originally Posted by ReDSanchous

I'd say в фразе. It seems to me that в/во фразе is hardly ever used in Russian. We normally say в этой фразе, в его фразе etc. What do you think?

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I'd better use 'во' too. 'в' before 'фр' sounds very bad. For example: во Франции, во фраке, во фракции, it will sound strange with 'в'

Maybe. Honestly, I'm a little confused about this.

I always want to say stuff like во твоей... Is that correct?

Quote:

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Originally Posted by ReDSanchous

I'd say в фразе. It seems to me that в/во фразе is hardly ever used in Russian. We normally say в этой фразе, в его фразе etc. What do you think?

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Во фразе: "Грека едет через реку",- неизвестный автор хотел выразить...

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Originally Posted by Darobat

I always want to say stuff like во твоей... Is that correct?

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No, it's not.