单选题 The sounds, which are produced by a closure in the vocal tract or by a narrowing which is so marked that air cannot escape without producing audible friction, are known as______.
【正确答案】 A
【答案解析】解析：考查辅音的定义。声道的某些部位受到挤压或阻碍，使得气流在口腔里转向、受阻或完全被阻挡，由此产生辅音。