Questions

Like many other Western European languages, English historically allowed questions to be formed by inverting the positions of verb and subject. Modern English permits this only in the case of a small class of verbs ("special verbs"), consisting of auxiliaries as well as forms of the copula be. To form a question from a sentence which does not have such an auxiliary or copula present, the auxiliary verb do (does, did) needs to be inserted, along with inversion of the word order, to form a question. For example:

• She can dance. → Can she dance? (inversion of subject she and auxiliary can)
• I am sitting here. → Am I sitting here? (inversion of subject I and copula am)
• The milk goes in the fridge. → Does the milk go in the fridge? (no special verb present; do-support required)

The above concerns yes-no questions, but inversion also takes place in the same way after other questions, formed with interrogative words such as where, what, how, etc. An exception applies when the interrogative word is the subject or part of the subject, in which case there is no inversion. For example:

• I go. → Where do I go? (wh-question formed using inversion, with do-support required in this case)
• He goes. → Who goes? (no inversion, because the question word who is the subject)

Note that inversion does not apply in indirect questions: I wonder where he is (not ... where is he). Indirect yes-no questions can be expressed using if or whether as the interrogative word: Ask them whether/if they saw him*.

Negative questions are formed similarly; however if the verb undergoing inversion has a contraction with not, then it is possible to invert the subject with this contraction as a whole. For example:

• John is going. (affirmative)
• John is not going. / John isn't going. (negative, with and without contraction)
• Isn't John going? / Is John not going? (negative question, with and without contraction respectively)

Tag questions are formed with a special verb and pronoun subject: isn't it?; were there?; am I not?