Tag Ending

A Tag ending is an abbreviated form of question which may be added to the end of any English sentence. It may be used, with varying intonation, to ask a question or simply to invite confirmation for some fact already known by speaker.

He can speak English well-can't he?

Mr. Smith is an American-isn't he?

Note that the tag ending, following a positive sentence, is always negative.

It is formed from the auxiliary verb used in the sentence (or from the verb to be) plus a personal pronoun which refers back to the subject and replaces the subject if the subject is noun. Note, further, that in sentences where there is no regular auxiliary verb, in the tag ending we introduce the normal auxiliary used in such sentences to form questions.

Examples:
He speaks English well-doesn't he?
Henry wrote that letter-didn't he?

Similarly when a tag ending is added to a negative sentences, the tag ending becomes positive in form.

Examples:
He doesn't speak English well-does he?
Henry didn't write that letter-did he?