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 Transport I wonder why．Romans wore togas and other questions about Rome / I wonder why planes have wings :: and other Questions about Transport /