【正确答案】A fricative is produced when there is close approximation of two articulators so that the airstream is partially obstructed and turbulent airflow is produced. The audible friction defines this class of sounds and thus explains the label "fricative".

【答案解析】[解析] 本题考查摩擦音。摩擦音——由发音器官造成的缝隙使气流产生摩擦而发出的声音。