If you mean what I think you mean, it would be better to say, "Eva and you are going in identical costumes."
No, but they can help when the grammar is incomplete or not strictly correct. For example, the correct grammatical interrogative form is "Are you going out?" But you can convey the same meaning if you say "You are going out" with your tone rising at the end of the sentence.
No, correct usage would be "...everyone is not the same"; as in, "Aren't you glad that everyone is not the same?".
Yes, "Can I have your name?" is a correct sentence. It is commonly used when asking someone for their name.
Use "I" when you are referring to the subject of a sentence, and use "me" when you are referring to the object. For example, "I am going to the store" (subject) and "She gave the book to me" (object).
Math is the correct spelling for this sentence. Maths can be the correct spelling for this sentence. In other words it depends on how you put it in a sentence. * * * * * English : Maths US : Math
Yes you can, in a sentence like 'i'm going the other way'.
David and you is correct. Easy way to remember is to make both singular in a sentence. You would say.. David is going to the store. You are going to the store. Not... David is going to the store. Yourself is going to the store. So when you combine the two they must make sense just as you would speak. David and you are going to the store. Hope this helps.
Both are correct, in is just an abbreviation for inside, so the sentences are the same.
No, because we do not end a sentence with the word 'at'. Simple asking "Where is she?" conveys the same inquiry, and 'at' is unnecessary.
there both the same
Whether it is technically correct to use both dashes and parentheses in the same sentence would depend on the structure of the sentence. On a practical level, however, that much punctuation might tend to confuse your readers.
Yes, but whether it means anything is unclear. A sentence may be grammatically correct and total gibberish at the same time.