Every culture has its body language. The way an Englishman crosses his legs is nothing like the way a male American does it. In talking, Americans are likely to end a statement with a lowering of the eyelids. They conclude a question with a lift of the hand or a widening of the eyes. With a future-tense verb they often gesture with a forward movement. There are regional idioms too. Your sex, ethnic background, social class and personal style all influence your body language. Nevertheless, you move and gesture within a certain idiom.Usually, the wordless communication acts to qualify the words. What the non-verbal elements express very often. and very efficiently, is the emotional side of the message. When a person feels liked or disliked, often it’s a case of "not what he said but the way he said it."Experts in the study of communication through body . movement 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 rejecting something. But there are other possible interpretations, too. The expert looks for patterns in the context, not for an isolated meaningful gesture. Which of the following is NOT a way of non-verbal communications according to the first paragraph（）

A. Waving a hand.
B. Making eye contact.
Changing positions in a chair.
D. Crying in a low voice.