Fantasy and ""soft"" sf: twelve recent tales, earnest, wide-ranging, and mostly slight, featuring a sometimes tedious succession of adolescent protagonists and problems. The one never-before-published yarn here is the best: a hard-hitting, explicitly feminist look at test-tube daughters in a delicately merciless school aboard an orbiting satellite. Also effective are the well-known ""A Letter from the Clearys""--about a post-nuclear-holocaust family--and an amusing tale of aerosol particles and odd coincidences. And, in a more ordinary vein, Willis offers: the famous title piece, wherein a time traveler helps save St. Paul's cathedral during the London Blitz; an alien who acquires the personality and motivations of those people nearby; survival after the sun goes nova; a silly Beauty and the Beast sequel; plus a ghostly lover, a half-baked swindler, and an orangutan. Studied, often over-controlled, and lacking bite--but with fair YA appeal.