We use affirmative word order in questions in spoken rather than written English. Declarative questions can be used when the speaker is fairly sure he has understood what has been said ...

In the following question, the WH-word who is the subject of the sentence ... correlated with the extent to which structures deviated from expected SVO order. On an English grammar test, students' ...

Word level grammar covers verbs and tenses ... sentence to show that something is being asked. Often a question changes the usual order of the words at the beginning of a sentence.