"What did you do yesterday?"
Translation:Що ви робили вчора?
The interwebs seem to have a complicated answer.
Учора - we write at the beginning of the sentence before the consonant; after punctuation marks; if the previous word ends, and the next word ends with a consonant. Учора мені прийшов лист. Сантехнік учора полагодив кран.
Вчора - we write in front of a word that begins with a vowel; if the previous word ends, and the next word ends with a vowel; after the vowel before the consonant. Вчора Ірина не ходила в школу. Саша вчора їв кашу на сніданок.
Ви is the formal form of “you,” used usually when addressing someone older than you, someone who has some form of authority over you (like your boss, parent, or a police officer), or someone of similar age with whom you are not well acquainted. Ти is the informal form of "you," most often used when speaking to a friend, a spouse, or a child; a decent and respectful boss, unless very friendly with you, would likely still call you ви. Very young children, like toddler age, will likely call their parents ти until they are old enough to know better, unless they have very strict and formal parents who demand to be called ви.
Ви is also used to address a group of more than one person. Words conjugated for a group are conjugated exactly the same as if speaking to someone formally. For example, ви зробили could either mean "you (formally) did," or "you (addressing a group) did."
Ви conjugations are not effected by gender, whether addressed to a group or when speaking formally to a single person. A group of females or males would still have робили just as a male or female police officer робили.
Below is a list of the formal pronouns of personal address and their informal counterparts.
Formal - informal
Ви - ти
Вас - тебе
Вам - тові
Ваш - твій
Ваша - твоя
Ваші - твої
Вами - тобою