Hi derek let my try to help you : 1. Dame los libros que te sobren & Dame los libros que te sobran. Questions: A. Are these two sentences have the exact same meaning? The two phrases are almost the same same but here we use them depending on the time where you use it: for example Dame los libros que te sobren is used whrn you are talking about the future like go to sell those books and bring me your sapare books and Dame los libros que te sobran is more like a present time like bring me yoor spare book that you already have now. B. Is there a difference on the things that each sentence emphasizes on? Not, just cahge the time for the action future and present. C. The subject in the later half of this setence is los libros? Yes D. So the usage of sobrar here is similar as the word tocar, when we say someone wins a lottery in Spanish?(le toca la loteria) im not familiar with that use of tocar, tocar is obviously user for touch something but is used too in colombia when you have to do something for a mandatory like you have to go to the bank we say te toco ir a el banco. sobrar is when you have excess of something in the phrases you have excess of books E. Why te is used here? What does it called grammatically? Is used to note about the spare book of the person with your are talking. Unforntunally i dont know how is grammatically called. 2. Los estudiantes que van-vayan a la excursión tienen que apuntarse ahora. Which one to choose here? Are the both right? If yes, what is the difference? If no, why? thats even more hard than the first one, when you use "van" is like is confirmed who will go to the excursion, but when you use "vayan" is when you did not had the certainty about how will go to the excursion. i do my best but let me tell you that you make me think about that jejejjeje.

Hello Derek! 1. Dame los libros que te sobren & Dame los libros que te sobran. Questions: A. Are these two sentences have the exact same meaning? Not exactly. The first one refers to the books those you have while in the second one you are using a hypotetic case. "If you have books left over, give me them" -> "Si te sobran libros dámelos" "Dame los libros que te sobren (si te sobran 'if they are left over')" Also it could be a kind of future: 'Give me the books left over those you will have'. B. Is there a difference on the things that each sentence emphasizes on? There are books in some, but in the second one the transmitter manifestly does not know which books will be left over. C. The subject in the later half of this sentence is los libros? No. The subject in both are "you". We don't mention it because in Spanish is very common to use the 'omitted subject'. D. So the usage of sobrar here is similar as the word tocar, when we say someone wins a lottery in Spanish?(le toca la loteria) No. 'Tocar', as you said, means both 'touch' and 'get' (in some contexts). 'Sobrar' is a verb to say when you have something that is left over. "Sobran pupitres en el salón, muchos alumnos no vinieron hoy porque están enfermos." "There are desks left over in the classroom; many students did not come because of illness." E. Why te is used here? What does it called grammatically? 'Te' replaces the indirect object. Is a short way to say 'a ti' ('to you'). Gramatically is a personal pronoun. Is, according to the RAE (Real Academia Española): 1. pron. person. Dative or accusative form of 2nd singular masculine and feminine person. It does not support preposition and when the verb is enclitic it is postponed to the verb.

2. Los estudiantes que van-vayan a la excursión tienen que apuntarse ahora. Which one to choose here? Are the both right? If yes, what is the difference? If no, why? Both are right, but the second one is more accurate. The sentence has subjunctive verb (vayan), something hypothetical, doubtful, possible desired that usually appears in subordinate clauses. (like in your first sentence) "The students whose go to the excursion have to sign in now" -> Is like say "not sign in if you will not go". I hope that I help you! ¡Saludos!