单选题
All of us communicate with one another nonverbally (不使用语言地), as well as with words. Most of the time we're not aware of it. We gesture with eyebrows or a hand, meet someone else's eyes and look away, change positions in a chair. In recent years researchers have discovered that there is a system to them almost as consistent and understandable as language. One important kind of body language is eye behavior. Americans are careful about how and when they meet one another's eyes. In our normal conversation, each eye contact lasts only about a second. When two Americans look searchingly into each other's eyes, they become more intimate. Therefore, we carefully avoid this, except in suitable situation. Researchers who are engaged in the study are not prepared to spell out a precise vocabulary of gestures. When an American rubs his nose, it may mean he is disagreeing with someone or refusing something. But there are other possible interpretations (解释), too. Another example, when a student in conversation with a professor holds the older man's eyes a little longer than is usual, it can be a sign of respect; it can be a challenge to the professor's authority (权威) ; it can be something else entirely. The researchers look for patterns in the situation, not for a separate meaningful gesture. Communication between human beings would be just dull if it were all done with words.