4Grammar and explanations
A second life for –ж байсан
You know –ж байна ("is doing") and its past –ж байсан ("was doing"). The same –ж байсан has a second meaning, and it is the one you hear in every interview: "have done, at least once in my life". It talks about your experience, not about one moment.
Би морь унаж байсан.I horse ride-CONV be-PAST"I have ridden a horse (before)."
Та Говьд очиж байсан уу?you Gobi-DAT go-CONV be-PAST Q"Have you ever been to the Gobi?"
The question and the answers
The yes/no question ends in уу, because байсан ends in a consonant and has back vowels. With a question word, байсан takes бэ, because it ends in н: Та хаана хаана очиж байсан бэ? "Where (all) have you been?"
The short answer repeats the verb: - Тийм, очиж байсан. "Yes, I have (been)." - Үгүй, очиж байгаагүй. "No, I haven't."
Never: –ж байгаагүй
The negative of experience is –ж байгаагүй: "have never done". Байгаагүй is the past negative of байх, built like the forms of lesson 54.
Би тэмээ унаж байгаагүй.I camel ride-CONV be-PAST-NEG"I have never ridden a camel."
Experience or "was doing"?
Both meanings use the same words, so the rest of the sentence decides. A precise moment in the past gives "was doing". Words like урьд нь (before), or a question about your life, give "have done".
Өчигдөр гурван цагт би хоол хийж байсан."Yesterday at three I was cooking."
Би урьд нь англи хэл зааж байсан."I have taught English before."
–сан or –ж байсан?
–сан reports a past event, often on a day you can name. –ж байсан in its second meaning says that something has happened in your life, without saying when.
Та өчигдөр музейд очсон уу?"Did you go to the museum yesterday?"
Та Хархоринд очиж байсан уу?"Have you ever been to Kharkhorin?"
Working as something: –аар ажиллах
To say what you work as, put the job in the instrumental: орчуулагчаар ажиллах (to work as an interpreter), багшаар ажиллах (to work as a teacher). The case that means "by bus" in автобусаар means "as" here.
Та орчуулагчаар ажиллаж байсан уу?you interpreter-INS work-CONV be-PAST Q"Have you ever worked as an interpreter?"
Go deeper in the grammar guide: The four Mongolian pasts · Saying no in Mongolian · The instrumental case