听力原文： In the past century, Taiji Quan has undergone significant changes, with its movements becoming more relaxed and graceful. Many moves requiring explosive strength disappeared. Eventually Taiji Quan became popular with men and women, young and old alike, and it can be used as an effective treatment. There were however, five main schools. Although each of the five had its own characteristic features, they share the following essentials. First, the posture is natural and relaxed. Motion remains even and fluid. The muscles should not be stiff or rigid. Breathing should be deep and regular. The practice of Taiji Quan requires a combination of vigor and gentleness. Secondly, the mind should be quiet but alert, with consciousness controlling the body, in order to achieve stillness within movement. Thirdly, body movements are well coordinated throughout the entire exercise period. Though the movements are gentle and slow, each part of the body is in constant motion. While practicing Taiji Quan, the weight of the body is mainly supported by the waist and legs. A characteristic feature of Taiji Quan is that all movements are carried out in half squatting position. (30)