Kids never stop asking questions. And Kathy Wollard, whose Los Angeles Times syndicated column "How come?" appears in newspapers around the world, never stops answering them. In five years since the first How Come? was published, Ms. Wollard has written hundreds of columns addressing the whys, whats, wheres, and hows sent in by her readers.<P> A direct follow-up to the original How Come?, How Come? Planet Earth is packed with lively, engagingly written, and often wittily illustrated answers to questions that kids have about the natural world around them. There are questions about animals - Why are electric eels electrical? (the charges not only help them find their way around in the dark, but act as a defense system). About human body - Where does the fat go when you lose weight? (it's burned up inside the muscles for energy). About Earth science - Why are storm clouds gray? (they contain a lot of water, which absorbs more sunlight than an ordinary cloud does, so storm clouds appear ominously dark). And just about everyday stuff - How do they make chewing gum? Why are diamonds the hardest material on Earth? Why do dogs bark?<P> For all kids who want to know (and all kids want to know), and for the parents who can't always explain it to them (no parents know every answer), How Come? Planet Earth is the perfect reference and companion. <P> <P>