文档介绍：Unit1 Public signs No parking It means you shouldn ’ t park. It means “ No parking ”. No littering It means you shouldn ’ t litter. It means “ No littering ”. Keep off the grass It means you shouldn ’ t walk on the grass. It means “ Keep off the grass ”. Be quiet It means you shouldn ’ t make noise. It means you should keep quiet. It means “ Be quiet ”. climb the tree .