Hi Irina, The "in vs. at" confusion is common, so I don't blame you for asking. When it comes to locations, we usually say "at." However, when it's important that we mention we were specifically inside, we'll use "in." Here's an example: A: Where are you right now? B: I'm at the cinema. A asked a very general question, and it's not important for B to tell A exactly where in the cinema he is, so he used "at." However... A: Did you hear about the fight outside? B: No, I'm in the cinema. What happened? Here, A wants to know if B heard about a specific event that happened at his location, but B didn't witness it because he was inside and the event took place outside, so B would use "in" because his specific location within the area in question is important. I hope this helps. Please let me know if my answer is confusing. If you want more information about "in vs. at (vs. on)," you can check out this link: https://www.englishclub.com/grammar/prepositions-place-at-in-on.htm

US: "movies" or "theater." We don't tend to use the word "cinema" in this fashion. "In" is about your relationship to the building. "At" is more general. I would say I'm "at the theater" if I am either inside the building or right outside of it. I would say "in the theater" if I have passed through the theater doors. Obviously, there is overlap between those two; if you are inside the building, you can use either word.

In American English: -- I was at the movies. <--- Indicates that you were also watching a movie. -- I was at a/the movie theater in Hadley, Massachusetts. <--- You may have been visiting a friend who worked there but not watching a movie. The word "the" indicates that there is only one movie theater in Hadley. The word "a" indicates that there are several. -- Jake: Where were you? -- Me: I was in the movie theater. <--- The movie theater is attached to the mall and he didn't know where I was. In this sentence, being inside the movie theater is the emphasis.

Thank you :) than more explanation I get than more I am confused :)

If you're in America, we also don't usually say cinema (we say "movie theater") so it might take a second for them to understand. If you're not in America, don't worry cinema is right :) If someone asks you where you are, you would say "I'm at the cinema", but if someone asked you where you saw a movie after it is out on Bluray you would say "I saw it in the cinema". If you mix the two phrases up it will be less natural, but the person will still understand what you are trying to say.