保护层的种类: sharp spines,strong shells,super scales 有刺的动物: lionfish,porcupine,pufferfish,hedgehog 有壳的动物: snail,clam,turtle 有鳞的动物: bird.lizard,crocodile,turtle,snake,fish,pangolin 疑问代词的用法，例如: what 指示代词的用法，例如: this,that, these 副词的用法，例如; quickly, slowly 连词的用法，例如:and,but,if,when 时间状语从句，例如: They shake and rattle when danger is near 定语从句，例如: A pufferfish has spines that lie flat.祈使句，例如: Stay away from a porcupine!