u/Mira_1453

For French speakers, does it sound unnatural when I mix up such prepositions? For example:saying ''I live in Japan.'' like ''J'habite dans Japon.'', not ''J'habite au Japon.''? Or saying ''I finished reading a book.'' like ''J'ai fini à lire un livre.", not "J'ai fini de lire un livre."? If I use a wrong preposition, then does it sound so unnatural that you guys don't get the meaning?

I am an 18-year-old university freshman majoring in Russian. You know, we are just beginners so we had one exam about cyrillic alphabet today. And we were asked to write down all the alphabet, both capital and small. But some of my friends did not write capital Ь and Ъ because no word in Russian starts with either of them. So I was wondering when do you guys actually use them? Is there any words that start with them??