''Hapax ''is ancient Greek for ''once, once only, once and for all,'' and ''onceness'' pervades this second book of poems by American expatriate poet A. E. Stallings. Opening with the jolt of ''Aftershocks,'' this book explores what does and does not survive its ''gone moment''--childhood (''The Dollhouse''), ancient artifacts (''Implements from the Grave of the Poet''), a marriage's lost moments of happiness (''Lovejoy Street''). The poems also often compare the ancient world with the modern Greece where Stallings has lived for several years. Her musical lyrics cover a range of subjects from love and family to characters and themes derived from classical Greek sources (''Actaeon'' and ''Sisyphus''). Employing sonnets, couplets, blank verse, haiku, Sapphics, even a sequence of limericks, Stallings displays a seemingly effortless mastery of form. She makes these diverse forms seem new and relevant as modes for expressing intelligent thought as well as charged emotions and a sense of humor. The unique sensibility and linguistic freshness of her work has already marked her as an important, young poet coming into her own.