[填空题] Dolphins are not the only animals 【B1】 humans that use sounds in an apparently intelligent manner. Whales also use a complex system of sounds 【B2】 is similar in many ways to a human language. One type of whale even sings, and its songs can 【B3】 on for as long as three or four hours. What is more, they can be heard under water at 【B4】 of more than 300 kilometers. After analyzing one of these songs with the aid of a computer, Carl Sagan said it 【B5】 at least a million "bits" of information. This is approximately the same 【B6】 of "bits" as in a long poem like The Odyssey. Chimpanzees also use a system of different sounds to communicate with each 【B7】 One type of cry 【B8】 to mean something like " danger in the air" or " big bird" and another apparently means "danger on the ground" or "snake". When they 【B9】 the first cry, they hide under trees or in holes and look up at the sky. The second cry causes them to hide in the upper 【B10】 of trees and to stare nervously at the