Inversion of Subjects and Verbs
Inversion of the subject and the verb is required when certain negative adverbs, such as never and nowhere, and adverbs that have a broadly negative meaning, such as hardly, little, only, rarely, scarcely and seldom, come before the subject in the sentence. Another word that triggers inversion and the insertion of an auxiliary verb is nor. The constructions with subject-verb inversion are a little more formal than those with if, but are used in everyday language nevertheless.