It is the same as in "a unit" (not an unit). Even though "unit" starts from a vowel letter, the first sound is consonant.
Before a noun beginning with a vowel (except e, я, and ю), об is used instead of o.
Edit: It depends on sound like olimo and Theron126 said. :)
It doesn't before these vowels because they actually start with a consonant й sound. Therefore I don't think it would become об before ё or probably и.
Why is this О pronounced as А in sentence audio but as О in single word click? Glitch?
in isolation the letter о is pronounced like о, but in a sentence о+Европе is pronounced like 1 word and therefore is pronounced like а
this happens with other prepositions and particles as well, such as не буду is pronounced ни буду
Prepositional/locative. The preposition "o" which means "about" needs to take the prepositional case.
Me too. But I'm fairly certain that it's not an accurate translation of думаю.
This sentece could be pragmatically wierd. There need to be a specific context if this sentence could be used. I think it's same for english sentence 'I think about Europe' is also same.
Я думаю о тебе (inf). or. Я думаю о вас (formal).
This is the prepositional or locative case:
Here are all the forms:
обо мне. about me о тебе about you о нём about him о ней about her о нём about it о нас about us о вас about you о них about them O means about. Use the form об when the next word starts with a vowel. Use обо only with мне.