Language is the most astonishing behavior in the animal kingdom. It is the species-typical behavior that sets humans completely (67) ________ from all other animals. Language is a means of communication, (68) ________ it is much more than that. Many animals can (69) ________ . The dance of the honeybee communicates the location of flowers (70) ________ other members of the hive (蜂群). But human language permits communication about anything, (71) ________ things like unicorns (独角兽) that have never existed. The key (72) ________ in the fact that the units of meaning, words, can be (73) ________ together in different ways, according to (74) ________ , to communicate different meanings. Language is the most important learning we do. Nothing (75) ________ humans so much as our ability to communicate abstract thoughts, (76) ________ about the universe, the mind, love, dreams or ordering a drink. It is an immensely complex (77) ________ that we take for granted. Indeed, we are not aware of most (78) ________ of our speech and understanding. Consider what happens when one person is speaking to (79) ________ . The speaker has to translate thoughts into (80) ________ language. Brain imaging studies suggest that the time from thoughts to the (81) ________ of speech is extremely fast, only 0.04 seconds! The listener must hear the sounds to (82) ________ out what the speaker means. He must use the sounds of speech to (83) ________ the words spoken, understand the pattern of (84) ________ of the words (sentences), and finally (85) ________ the meaning. This takes somewhat longer, a minimum of about 0.5 seconds. But 86 started, it is of course a continuous process.

A．to
B．from
C．over
D．on