I'm pretty sure I have to use the in 'The people/citizens of this city speak a dialect' but when I try to use another preposition, instead of of, it doesn't seem right. I don't know why. Do I have to use 'the' in the following sentences assuming that those things have never been mentioned before in a conversation. I'm talking the specific use of the definite article
(The) people in the city still speak a dialect. (not just any people but those who live in this city)
(The) shirts in this store are cheap (.....in this store)
(The) Americans in Russia try to learn the Russian language (and so on)
I don't like (the) reviews on this site
I read (the) books by John Summers
Or there's a difference in the meaning with and without the definite article?