The phenomenon of third tone (T3) sandhi in Mandarin Chinese has long been noticed: underlying full T3s may be modified under the influence of their tonal phonetic environment. By discussing in detail from the perspectives of perception, historical... of Chinese tone sandhi-that all of it has originated because of historical change of tones by showing that T3 sandhi is a special phenomenon that distinguishes itself from other sandhi. Also, the conclusion has pedagogical implications which can help language