I actually make an effort to pronounce Latin 'ae' as /ae/ (tense open front/central unrounded vowel)+(tense mid front unrounded vowel)). However, when I hear a classicist pronounce Latin 'ae', it does indeed come out basically as an English long ī in their own dialect ((tense open front/central unrounded vowel)+(tense high front unrounded vowel (or /y/ off-glide))).
I suspect the Roman pronunciation was closer to /ae/ than to English ī, that is, with a slightly lower ending vowel. Since we don't have /ae/ in standard English, but we do have /ai/ (as in "bye"), it would be hard for American or British speakers to hear the difference between /ae/ and /ai/, anyway.
TL;DR English 'ī' for Latin 'ae' probably isn't exactly right, but you'll need to get used to it.
I have a problem with this American English. For me a city has to have a cathedral, therefore, almost all urbs are towns. Sometimes town is accepted as a translation and sometimes it isn't. Also, there is no option in the reporting list that enables a correct report in such cases.
Here is a British definition of city: "a place where many people live, with many houses, stores, businesses, etc., and which is bigger than a town: " From the Cambridge Dictionary. https://dictionary.cambridge.org/us/dictionary/english/city
Beijing is a very large city. I don't know if it has a cathedral--but I am sure it is not prominent-- definitely not a defining characteristic of Beijing
What do you call Istanbul and Beijing?-- towns? I suspect that Istanbul does not center around a cathedral. And I bet its mosques are much more prominent.
Like us, the Romans had different words for "city" and "town" ("Urbs" mostly referred to Rome and the large towns of Gaul).
The word for "town" would be "oppidum."
In the days of Julius Caesar, you are right, most locations would have been considered "oppidi." The application here belongs completely to DL, and their conceptualization of "Urbs" is mostly based off of the modern American word "city," which actually has a different connotation from both the classical sense of "city" and the Latin word "Urbs."
Hope this helps!
mihi and tibi are Dative forms of me and you (singular familar form of you) An indirect object is an example of something that would be Dative.
mei is my while tei is your (Genitive forms of me and of you)
The word "liberi" can also mean "sons" or "children". I wonder though if it originally applied to sons of free citizens. https://www.online-latin-dictionary.com/latin-english-dictionary.php?lemma=LIBER200#
Keep in mind that "Filii" is the masculine "sons" or "children" that we learned at Duolingo so far and "Filiae" is the feminine plural for "daughters" or "children".