All the pages in this part of the site have quiz questions. In the answers to the questions I have used the words correct/incorrect, right/wrong, possible/impossible, usual/unusual, standard/non-standard or likely/unlikely. These words need some explanation.
English, like all languages, is not set in stone. It is very flexible and constantly changing. Furthermore, there is not one English; there is British English, American English, New Zealand English, Black English, Scottish English, Liverpool English, and so on. Of course there is considerable overlap between these varieties of English but what is correct or usual in one of the varieties may not be so in another.
However, it is impossible for me take all this variation into account in these pages, and since I am British I will start from what is sometimes called BBC English. I will apply the terms correct/usual/standard etc. on the basis of what is correct/usual or standard in BBC English.
Wrong/incorrect/impossible: When I say that an expression is wrong or incorrect or impossible, then I mean that it is grammatically unacceptable. So, Why you do that? is just plain wrong as a way to express the question: Why are you doing that? or Why do you do that? or Why did you do that?
Non-standard:I didn't see nothing!Double negatives like this are common in some English varieties but they are unacceptable in BBC English. Problematic usage of this kind will be referred to as non-standard (or non-British-English-standard) in my answers.
Unusual:This is very powerful coffee! In no way is this sentence incorrect, but powerful is not the usual adjective to use with the noun coffee - strong coffee is much more common. English speakers, however, can and do create uncommon combinations of words when they want to achieve a particular effect. I will use the word unusual to refer to this kind of problematic use of English.
Unlikely: An expression is described as unlikely if it is grammatically correct, standard BBC usage but the situation in which it would be the usual way to express a particular meaning is unlikely to occur. For example: How did you get that black eye? is much more likely than How have you got that black eye?, but a situation could conceivably occur in which the latter sentence is the right way to express the question.