Question

they are singing well question tag

Answer 1

Qustn tag -
Arn't they?

Answer 2

Given sentence:

They are singing well.

Sentence after adding appropriate question tag:

They are singing well, aren't they?

Additional information:

Question tag may be simply and compactly defined as a single phrase or group of words that is added at the end of a statement or sentence in order to and converts it to a question.

The British English call it "Question Tag" whereas on the other hand American English call it "Tag Question" or "Tail Question".

Question tags are generally common in familiar conversation and not in formal writing or conversation.