I wonder how Romans made an expression for "What do you do?"?
Both "quid tu agis?" and "quid tu facis?" are possible?
And also how did they pronounce three vowels in a word like
'quae,quaerere'? in qUIte or qUEstion in English?
Both “Quid agis?” and “Quid facis?” correspond to "What do you do?".
Note that the 2nd person pronoun “tu” is omitted because it is implied in the verb forms “agis/facis” which are just a 2nd person singular.
Anyway, if the English “you” (which in English is either a 2nd person singular or a 2nd person plural) is used as a 2nd person plural, in Latin the phrase "What do you do?" must be translated as “Quid agitis?” or “Quid facitis?” in the 2nd person plural of the Latin verb forms.
As for the pronunciation of three vowels in a word like “quae” and “quaerere”, it is the same as the pronunciation of “qUE” in the English word “ qUEstion “, that is to say that you must pronounce “quae” in both “quae” and “quaerere” like “qUE” in the English word “ qUEstion “.