No, and you already did by typing that lowercase 'I'.
You were - This is correct. You were the best in the team.
The correct grammar would be "Either you or I am wrong." This form matches the subject-verb agreement between "you" and "I."
Snobbish girl is correct but your question is not.Written correctly, your question would be:Is snobbish girl correct grammar?
no, it's grammatically wrong
Grammar is tricky. If you did not learn it as a child, the best way to learn it (and know whether your grammar is correct) is to find someone who speaks correct grammar and listen to them, a lot. NPR is a good place to listen to people who have good grammar.
The sentence "I arrived exactly at their cut off time" is not correct grammar because of the wrong diction used.
Neither: "is died" is wrong".The correct form is "a patient died from cancer".
The words Yeolla Daebak are not translatable into English. It is not clear if it is correct grammar or not.
That is not correct grammar. A better sentence would be "I went to the supermarket and found this item." In the proper sentence, there is an object and better structure.
No, the correct grammar would be, "Should I remain unmarried rather than get married to him?"
Wrong spelling is the incorrect spelling of a word. Wrong grammar has a much broader meaning and can include using a word in the incorrect tense or sense, or inserting or omitting punctuation.
If you mean as in "This here rifle has a hair trigger," it is substandard, but not wrong. Don't use it in writing.