Sentence improvement — Stative verb usage: replace the ungrammatical progressive form in ‘‘This telephone number is not existing’’ with the standard simple present for states.

Given data
Original: ‘‘This telephone number is not existing.’’

Concept/Approach
Stative verbs like ‘‘exist’’ typically do not take progressive aspect. The natural correction is the simple present negative: ‘‘does not exist.’’

Option analysis
has not existed — Present perfect suggests a period up to now; possible but needlessly marked.does not exist — Correct, direct, and idiomatic.has not been existing — Progressive perfect is unidiomatic with ‘‘exist.’’No improvement — Keeps the incorrect progressive.is not in existence — Grammatically fine but verbose; simple present is preferred.

Verification/Alternative
Model: ‘‘Such a record does not exist.’’

Common pitfalls
Applying ‘‘be + -ing’’ to stative verbs (know, own, believe, exist) in neutral prose.

Final Answer
does not exist