The right answer is
Elephants emit low-frequency sounds, believed to originate from a small area on their foreheads, that they may use as a "secret language" to communicate with other members of the herd. 但我觉得分词做插入时,总有修饰对象不明的问题(believed 既可修饰sounds,又可修饰主句.) ,比如说,下面是一句错句: In her book illustrations, carefully coordinating them with her narratives, Beatrix Potter capitalized on her keen observation and love of the natual world. 原因是coordinating既可修饰illustrations,又可修饰主句. 请高手指教! | 
