I wonder why zippers have teeth and other questions about inventions I wonder why.zippers have teeth and other questions about inventions / Zippers have teeth and other questions about inventions / I wonder why trees have leaves and other questions about plants I wonder why camels have humps and other questions about animals I wonder why planes have wings and other questions about transport I wonder why trees have leaves :and other questions about plants I wonder why planes have wings and other questions about transportation I wonder why romans wore togas and other questions about ancient rome I wonder why leaves change color and other questions about plants