This could be either "I don't have his trousers" or "I don't have her trousers" So if soui means her or his, what phrase can I use to be specific?
the person you'll be talking to will understand what you mean based on who you are talking about
It's good that Duolingo can differentiate between UK and US English. It seems us Brits stands alone, while everywhere else uses some form of "pants" instead of the word "trousers". However, we use pants (male, US shorts) and panties (female) for underwear.
We typically say boxers, shorts are any short-leg summer wear. If it makes you feel any better I'm an American sharing an office with two Brits who smirk at me whenever I talk about my pants ;)
Both "i vostri pantaloni" and "i suoi pantaloni" can be formal but "vostri" is not used anymore
In writing to be formal normally you will use capital letter Lei vs lei Suo vs suo etc....
i wrote i don't have her pants why it was wrong ? suoi means her or his
How does one know if the person/people's gender or if it is singular or plural?
If it can mean his or hers, why can't I use 'theirs', to be gender non-specific?
I wrote i do not have his trousers and i go it wrong! Why? They said it's i do not have his pants!! Hey! ragazzi dimmi se questo è giusto
The tua tuo suo sua dilemma, in this case, "suoi" for plural. I found this confusing too, the duolingo answer is "I do not have his pants." the answer should be " "I do not have his/her pants." I put in "I do not have her pants." duolingo marked correct as it should. Try it next time both are correct. REMEMBER, the gender follows the word, not the subject.