English grammar error-spotting (question tags—match auxiliary, tense, and subject): ‘‘She sang / very well / isn't it? / No error.’’ Choose the erroneous segment.

Concept / Approach
Question tags must agree with the auxiliary/tense and subject of the main clause. Main clause: simple past (‘‘sang’’) with subject ‘‘she’’; tag → ‘‘didn’t she?’’

Correction
‘‘She sang very well, didn’t she?’’

Common pitfalls

• Using a present-tense ‘‘isn’t it?’’ tag for a past-tense statement.

Final Answer
isn't it?