how do I know if it means: "Tim is my dog", or "Tim, this is my dog" ?
I am a total beginner, and this sentence is confusing to me. "Тим — моя любимая собака" - I thought it meant "Tim, (this is) my favorite dog." Apparently the right answer is "Tim is my favorite dog".
Can you please help explain this to me? Thank you so much!
"Tim, this is my favorite dog" = "Тим, это моя любимая собака".
"Tim is my favorite dog" = "Тим - это моя любимая собака" or "Тим - моя любимая собака".
The difference between "Тим, это моя любимая собака" and "Тим - это моя любимая собака" (apart from the punctuation) is intonation. In the first sentence there is a stress on the word это.
Тим - моя любимая собака = Tim is my favorite dog. Here, Tim is dog's name. The Russians omit "is". Tim, this is my dog. Here Tim could be man's name or dog's name. Then: 1. Тим, это моя собака (I say to Tim that it is my dog.) 2. Тим - это моя собака. (Tim is dog's name and it is my dog).
Notice dash between "Тим" анд "моя"? In sentences like this it fulfills the function of the omitted word "есть" ("is").
Simple answer is context. Russian sentence structure is more fluent , some words might be omitted (and some are always omitted like articles and auxiliary verbs) so a lot is understood from context - makes it inconvenient to use russian for programming, but among humans shouldnt pose a problem. In speech it will also be aided by intonation (which is why we have a rather complex punctuation system).
Only way it might be a problem is for duolingo test, but if you are talking to a person everything becomes that much easier because likely they know their own name and can distinguish when a name is part of the address or part of the message. Granted mistakes CAN happen, but such is life