Sheepish Riddles

This Easy-to-Read offering from Hall and Eisenberg (Snakey Riddles, 1990, etc.) has its ups and downs, but for the most part its cleverness shines through. Much of the material will have young readers giggling along: A ''baa humbug'' is the result of crossing a sheep with a bee; and ''Steal wool'' comes of crossing sheep and a thief. But there are also groaners, including riddles about sheep who count people when they can't sleep, and Cinderella Sheep's lost ''grass'' slipper may not elicit much response from children old enough to read this on their own. Some of the funniest lines aren't riddles at all, but throwaway comments contained in the illustrations (when they go to the movies, don't all sheep order ''baaattered'' popcorn?). Alley's lush artwork has real comic sense and keeps readers cackling even when the riddles go astray. (Picture book. 4-8)--KK 01/15/1996.