Tag questions

A tag question is a short yes-no question appended to a statement, usually a declarative sentence:

(1) Peter lives here, doesn't he?

The main statement is highlighted in blue, and the tag question in orange.

The tag question consists of two parts: an operator and a pronoun. In  (1), the operator is doesn't and the pronoun is he.

There are three important things to learn about a tag question.

Firstly, the tag question is negative if the statement is positive and vice versa:

(2) She drives a BMW, doesn't she?
(3) She doesn't drive, does she?

Secondly, the choice of operator is related to the verb in the statement. In general, the type of verb and the corresponding operator can be divided into the three groups below:

i) With auxiliary verbs, the operator is formed with the auxiliary verb:

(4) He is working today, isn't he?
(5) They weren't at the party, were they?
(6) We have seen this before, haven't we?

ii) With modal verbs, the operator is formed with the modal verb:

(4) He can sue the paper, can't he?
(5) The children couldn't hear us, could they?
(6) She won't lie to us, will she?

iii)  If the main verb is neither an auxiliary nor modal verb, the question tag uses an appropriate form of do:

(7) Sally plays tennis, doesn't she?
(8) The two boys swam in the river, didn't they?
(9) You don't live here, do you?

But note the exceptions below:

(10) I'm the tallest, aren't I? (informally)
(11) She has a talent for singing, doesn't she?

The formal equivalent of (10) is (12) below:

(12) I am the tallest person, am I not?

Thirdly, the pronoun in the tag refers to the subject in the main clause:

(13) Sue came last night, didn't she?
(14) His dogs are fierce, aren't they?
(15) Mary and her friends will be here soon, won't they?
(16) These oranges are sweet, aren't they?