In Chinese, every word has its own pronunciation and tone. The word "crab" consists of two Chinese characters, namely "páng" and "xiè". According to the phonetic rules of Putonghua, the pronunciation needs to be marked with tones. The tone of "páng" is the second tone (from low to high), and the tone of "xiè" is the fourth tone (from high to low). The word "crab" is classified as a disyllabic word, that is, it contains two different basic phonetic units, so it is necessary to pay attention to accurately grasp their corresponding pronunciation methods and priorities.